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util: Introduce a parser for kernel cmdline arguments
Introduce two utility functions to parse a kernel command line string according to the kernel code parsing rules in order to enable the caller to perform operations such as verifying whether certain argument=value combinations are present or retrieving an argument's value. Signed-off-by: Paulo de Rezende Pinatti <ppinatti@linux.ibm.com> Signed-off-by: Boris Fiuczynski <fiuczy@linux.ibm.com> Reviewed-by: Erik Skultety <eskultet@redhat.com>
This commit is contained in:
Paulo de Rezende Pinatti
Erik Skultety
parent
1eabe312ea
commit
c5fffb959d
@ -3433,6 +3433,8 @@ virGetUserShell;
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virHostGetDRMRenderNode;
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virHostHasIOMMU;
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virIndexToDiskName;
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virKernelCmdlineMatchParam;
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virKernelCmdlineNextParam;
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virMemoryLimitIsSet;
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virMemoryLimitTruncate;
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virMemoryMaxValue;
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@ -1701,6 +1701,192 @@ virHostGetDRMRenderNode(void)
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return ret;
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}
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static const char *virKernelCmdlineSkipQuote(const char *cmdline,
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bool *is_quoted)
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{
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if (cmdline[0] == '"') {
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*is_quoted = !(*is_quoted);
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cmdline++;
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}
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return cmdline;
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}
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/**
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* virKernelCmdlineFindEqual:
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* @cmdline: target kernel command line string
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* @is_quoted: indicates whether the string begins with quotes
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* @res: pointer to the position immediately after the parsed parameter,
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* can be used in subsequent calls to process further parameters until
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* the end of the string.
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*
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* Iterate over the provided kernel command line string while honoring
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* the kernel quoting rules and returns the index of the equal sign
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* separating argument and value.
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*
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* Returns 0 for the cases where no equal sign is found or the argument
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* itself begins with the equal sign (both cases indicating that the
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* argument has no value). Otherwise, returns the index of the equal
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* sign in the string.
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*/
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static size_t virKernelCmdlineFindEqual(const char *cmdline,
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bool is_quoted,
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const char **res)
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{
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size_t i;
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size_t equal_index = 0;
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for (i = 0; cmdline[i]; i++) {
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if (!(is_quoted) && g_ascii_isspace(cmdline[i]))
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break;
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if (equal_index == 0 && cmdline[i] == '=') {
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equal_index = i;
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continue;
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}
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virKernelCmdlineSkipQuote(cmdline + i, &is_quoted);
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}
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*res = cmdline + i;
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return equal_index;
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}
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static char* virKernelArgNormalize(const char *arg)
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{
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return virStringReplace(arg, "_", "-");
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}
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/**
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* virKernelCmdlineNextParam:
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* @cmdline: kernel command line string to be checked for next parameter
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* @param: pointer to hold retrieved parameter, will be NULL if none found
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* @val: pointer to hold retrieved value of @param
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*
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* Parse the kernel cmdline and store the next parameter in @param
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* and the value of @param in @val which can be NULL if @param has
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* no value. In addition returns the address right after @param=@value
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* for possible further processing.
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*
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* Returns a pointer to address right after @param=@val in the
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* kernel command line, will point to the string's end (NULL)
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* in case no next parameter is found
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*/
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const char *virKernelCmdlineNextParam(const char *cmdline,
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char **param,
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char **val)
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{
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const char *next;
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int equal_index;
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bool is_quoted = false;
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*param = NULL;
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*val = NULL;
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virSkipSpaces(&cmdline);
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cmdline = virKernelCmdlineSkipQuote(cmdline, &is_quoted);
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equal_index = virKernelCmdlineFindEqual(cmdline, is_quoted, &next);
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if (next == cmdline)
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return next;
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/* param has no value */
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if (equal_index == 0) {
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if (is_quoted && next[-1] == '"')
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*param = g_strndup(cmdline, next - cmdline - 1);
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else
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*param = g_strndup(cmdline, next - cmdline);
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return next;
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}
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*param = g_strndup(cmdline, equal_index);
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if (cmdline[equal_index + 1] == '"') {
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is_quoted = true;
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equal_index++;
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}
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if (is_quoted && next[-1] == '"')
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*val = g_strndup(cmdline + equal_index + 1,
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next - cmdline - equal_index - 2);
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else
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*val = g_strndup(cmdline + equal_index + 1,
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next - cmdline - equal_index - 1);
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return next;
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}
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static bool virKernelCmdlineStrCmp(const char *kernel_val,
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const char *caller_val,
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virKernelCmdlineFlags flags)
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{
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if (flags & VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX)
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return STRPREFIX(kernel_val, caller_val);
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return STREQ(kernel_val, caller_val);
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}
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/**
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* virKernelCmdlineMatchParam:
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* @cmdline: kernel command line string to be checked for @arg
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* @arg: kernel command line argument
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* @values: array of possible values to match @arg
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* @len_values: size of array, it can be 0 meaning a match will be positive if
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* the argument has no value.
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* @flags: bitwise-OR of virKernelCmdlineFlags
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*
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* Try to match the provided kernel cmdline string with the provided @arg
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* and the list @values of possible values according to the matching strategy
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* defined in @flags.
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*
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*
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* Returns true if a match is found, false otherwise
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*/
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bool virKernelCmdlineMatchParam(const char *cmdline,
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const char *arg,
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const char **values,
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size_t len_values,
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virKernelCmdlineFlags flags)
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{
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bool match = false;
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size_t i;
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const char *next = cmdline;
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g_autofree char *arg_norm = virKernelArgNormalize(arg);
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while (next[0] != '\0') {
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g_autofree char *kparam = NULL;
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g_autofree char *kparam_norm = NULL;
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g_autofree char *kval = NULL;
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next = virKernelCmdlineNextParam(next, &kparam, &kval);
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if (!kparam)
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break;
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kparam_norm = virKernelArgNormalize(kparam);
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if (STRNEQ(kparam_norm, arg_norm))
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continue;
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if (!kval) {
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match = (len_values == 0) ? true : false;
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} else {
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match = false;
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for (i = 0; i < len_values; i++) {
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if (virKernelCmdlineStrCmp(kval, values[i], flags)) {
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match = true;
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break;
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}
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}
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}
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if (match && (flags & VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST))
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break;
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}
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return match;
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}
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/*
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* Get a password from the console input stream.
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* The caller must free the returned password.
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@ -145,6 +145,40 @@ bool virHostHasIOMMU(void);
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char *virHostGetDRMRenderNode(void) G_GNUC_NO_INLINE;
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/* Kernel cmdline match and comparison strategy for arg=value pairs */
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typedef enum {
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/* substring comparison of argument values */
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VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX = 1,
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/* strict string comparison of argument values */
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VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ = 2,
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/* look for any occurrence of the argument with the expected value,
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* this should be used when an argument set to the expected value overrides
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* all the other occurrences of the argument, e.g. when looking for 'arg=1'
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* in 'arg=0 arg=1 arg=0' the search would succeed with this flag
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*/
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VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST = 4,
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/* look for the last occurrence of argument with the expected value,
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* this should be used when the last occurrence of the argument overrides
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* all the other ones, e.g. when looking for 'arg=1' in 'arg=0 arg=1' the
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* search would succeed with this flag, but in 'arg=1 arg=0' it would not,
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* because 'arg=0' overrides all the previous occurrences of 'arg'
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*/
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VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST = 8,
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} virKernelCmdlineFlags;
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const char *virKernelCmdlineNextParam(const char *cmdline,
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char **param,
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char **val);
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bool virKernelCmdlineMatchParam(const char *cmdline,
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const char *arg,
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const char **values,
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size_t len_values,
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virKernelCmdlineFlags flags);
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/**
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* VIR_ASSIGN_IS_OVERFLOW:
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* @rvalue: value that is checked (evaluated twice)
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136
tests/utiltest.c
136
tests/utiltest.c
@ -254,6 +254,140 @@ testOverflowCheckMacro(const void *data G_GNUC_UNUSED)
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}
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struct testKernelCmdlineNextParamData
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{
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const char *cmdline;
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const char *param;
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const char *val;
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const char *next;
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};
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static struct testKernelCmdlineNextParamData kEntries[] = {
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{ "arg1 arg2 arg3=val1", "arg1", NULL, " arg2 arg3=val1" },
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{ "arg1=val1 arg2 arg3=val3 arg4", "arg1", "val1", " arg2 arg3=val3 arg4" },
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{ "arg1=sub1=val1,sub2=val2 arg3=val3 arg4", "arg1", "sub1=val1,sub2=val2", " arg3=val3 arg4" },
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{ "arg3=val3 ", "arg3", "val3", " " },
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{ "arg3=val3", "arg3", "val3", "" },
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{ "arg-3=val3 arg4", "arg-3", "val3", " arg4" },
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{ " arg_3=val3 arg4", "arg_3", "val3", " arg4" },
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{ "arg2=\"value with space\" arg3=val3", "arg2", "value with space", " arg3=val3" },
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{ " arg2=\"value with space\" arg3=val3", "arg2", "value with space", " arg3=val3" },
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{ " \"arg2=value with space\" arg3=val3", "arg2", "value with space", " arg3=val3" },
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{ "arg2=\"val\"ue arg3", "arg2", "val\"ue", " arg3" },
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{ "arg2=value\" long\" arg3", "arg2", "value\" long\"", " arg3" },
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{ " \"arg2 with space=value with space\" arg3", "arg2 with space", "value with space", " arg3" },
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{ " arg2\" with space=val2\" arg3", "arg2\" with space", "val2\"", " arg3" },
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{ " arg2longer=someval\" long\" arg2=val2", "arg2longer", "someval\" long\"", " arg2=val2" },
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{ "=val1 arg2=val2", "=val1", NULL, " arg2=val2" },
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{ " ", NULL, NULL, "" },
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{ "", NULL, NULL, "" },
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};
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static int
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testKernelCmdlineNextParam(const void *data G_GNUC_UNUSED)
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{
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const char *next;
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size_t i;
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for (i = 0; i < G_N_ELEMENTS(kEntries); ++i) {
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g_autofree char * param = NULL;
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g_autofree char * val = NULL;
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next = virKernelCmdlineNextParam(kEntries[i].cmdline, ¶m, &val);
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if (STRNEQ_NULLABLE(param, kEntries[i].param) ||
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STRNEQ_NULLABLE(val, kEntries[i].val) ||
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STRNEQ(next, kEntries[i].next)) {
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VIR_TEST_DEBUG("\nKernel cmdline [%s]", kEntries[i].cmdline);
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VIR_TEST_DEBUG("Expect param [%s]", kEntries[i].param);
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VIR_TEST_DEBUG("Actual param [%s]", param);
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VIR_TEST_DEBUG("Expect value [%s]", kEntries[i].val);
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VIR_TEST_DEBUG("Actual value [%s]", val);
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VIR_TEST_DEBUG("Expect next [%s]", kEntries[i].next);
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VIR_TEST_DEBUG("Actual next [%s]", next);
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return -1;
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}
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}
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return 0;
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}
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struct testKernelCmdlineMatchData
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{
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const char *cmdline;
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const char *arg;
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const char *values[2];
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virKernelCmdlineFlags flags;
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bool result;
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};
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static struct testKernelCmdlineMatchData kMatchEntries[] = {
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"1", "y"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, false },
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"on", "yes"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, true },
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"1", "y"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST | VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX, true },
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"a", "b"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST | VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX, false },
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"on", "yes"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, false },
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{"arg1 myarg=no arg2=val2 myarg=yes arg4=val4 myarg=no arg5", "myarg", {"1", "y"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX, false },
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{"arg1 myarg=no arg2=val2 arg4=val4 myarg=yes arg5", "myarg", {"on", "yes"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, true },
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{"arg1 myarg=no arg2=val2 arg4=val4 myarg=yes arg5", "myarg", {"1", "y"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX, true },
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{"arg1 myarg=no arg2=val2 arg4=val4 myarg arg5", "myarg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, true },
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{"arg1 myarg arg2=val2 arg4=val4 myarg=yes arg5", "myarg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST, true },
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{"arg1 myarg arg2=val2 arg4=val4 myarg=yes arg5", "myarg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, false },
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{"arg1 my-arg=no arg2=val2 arg4=val4 my_arg=yes arg5", "my-arg", {"on", "yes"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, true },
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{"arg1 my-arg=no arg2=val2 arg4=val4 my_arg=yes arg5 ", "my-arg", {"on", "yes"}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, true },
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{"arg1 my-arg arg2=val2 arg4=val4 my_arg=yes arg5", "my_arg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST, true },
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{"arg1 my-arg arg2=val2 arg4=val4 my-arg=yes arg5", "my_arg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST, true },
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{"=arg1 my-arg arg2=val2 arg4=val4 my-arg=yes arg5", "my_arg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST, true },
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{"my-arg =arg1 arg2=val2 arg4=val4 my-arg=yes arg5", "=arg1", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, true },
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{"arg1 arg2=val2 myarg=sub1=val1 arg5", "myarg", {"sub1=val1", NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, true },
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{"arg1 arg2=", "arg2", {"", ""}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST | VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ, true },
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{" ", "myarg", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, false },
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{"", "", {NULL, NULL}, VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST, false },
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};
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static int
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testKernelCmdlineMatchParam(const void *data G_GNUC_UNUSED)
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{
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bool result;
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size_t i, lenValues;
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for (i = 0; i < G_N_ELEMENTS(kMatchEntries); ++i) {
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if (kMatchEntries[i].values[0] == NULL)
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lenValues = 0;
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else
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lenValues = G_N_ELEMENTS(kMatchEntries[i].values);
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result = virKernelCmdlineMatchParam(kMatchEntries[i].cmdline,
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kMatchEntries[i].arg,
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kMatchEntries[i].values,
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lenValues,
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kMatchEntries[i].flags);
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if (result != kMatchEntries[i].result) {
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VIR_TEST_DEBUG("\nKernel cmdline [%s]", kMatchEntries[i].cmdline);
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VIR_TEST_DEBUG("Kernel argument [%s]", kMatchEntries[i].arg);
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VIR_TEST_DEBUG("Kernel values [%s] [%s]", kMatchEntries[i].values[0],
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kMatchEntries[i].values[1]);
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if (kMatchEntries[i].flags & VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX)
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VIR_TEST_DEBUG("Flag [VIR_KERNEL_CMDLINE_FLAGS_CMP_PREFIX]");
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if (kMatchEntries[i].flags & VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ)
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VIR_TEST_DEBUG("Flag [VIR_KERNEL_CMDLINE_FLAGS_CMP_EQ]");
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if (kMatchEntries[i].flags & VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST)
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VIR_TEST_DEBUG("Flag [VIR_KERNEL_CMDLINE_FLAGS_SEARCH_FIRST]");
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if (kMatchEntries[i].flags & VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST)
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VIR_TEST_DEBUG("Flag [VIR_KERNEL_CMDLINE_FLAGS_SEARCH_LAST]");
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VIR_TEST_DEBUG("Expect result [%d]", kMatchEntries[i].result);
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VIR_TEST_DEBUG("Actual result [%d]", result);
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return -1;
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}
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}
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return 0;
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}
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static int
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@ -277,6 +411,8 @@ mymain(void)
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DO_TEST(ParseVersionString);
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DO_TEST(RoundValueToPowerOfTwo);
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DO_TEST(OverflowCheckMacro);
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DO_TEST(KernelCmdlineNextParam);
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DO_TEST(KernelCmdlineMatchParam);
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|
||||
return result == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user