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Functions and structures in lineread.c use plain int to record and report the length of lines we receive. This means we truncate the result from read(2) in some circumstances. Use ssize_t to avoid that. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* PASST - Plug A Simple Socket Transport
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* for qemu/UNIX domain socket mode
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*
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* PASTA - Pack A Subtle Tap Abstraction
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* for network namespace/tap device mode
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*
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* lineread.c - Allocation free line-by-line buffered file input
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*
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* Copyright Red Hat
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* Author: David Gibson <david@gibson.dropbear.id.au>
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*/
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#include <stddef.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include "lineread.h"
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#include "util.h"
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/**
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* lineread_init() - Prepare for line by line file reading without allocation
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* @lr: Line reader state structure to initialize
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* @fd: File descriptor to read lines from
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*/
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void lineread_init(struct lineread *lr, int fd)
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{
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lr->fd = fd;
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lr->next_line = lr->count = 0;
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}
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/**
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* peek_line() - Find and NULL-terminate next line in buffer
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* @lr: Line reader state structure
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* @eof: Caller indicates end-of-file was already found by read()
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*
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* Return: length of line in bytes, -1 if no line was found
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*/
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static ssize_t peek_line(struct lineread *lr, bool eof)
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{
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char *nl;
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/* Sanity checks (which also document invariants) */
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ASSERT(lr->next_line + lr->count >= lr->next_line);
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ASSERT(lr->next_line + lr->count <= LINEREAD_BUFFER_SIZE);
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nl = memchr(lr->buf + lr->next_line, '\n', lr->count);
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if (nl) {
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*nl = '\0';
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return nl - lr->buf - lr->next_line + 1;
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}
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if (eof) {
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lr->buf[lr->next_line + lr->count] = '\0';
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/* No trailing newline, so treat all remaining bytes
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* as the last line
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*/
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return lr->count;
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}
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return -1;
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}
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/**
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* lineread_get() - Read a single line from file (no allocation)
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* @lr: Line reader state structure
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* @line: Place a pointer to the next line in this variable
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*
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* Return: Length of line read on success, 0 on EOF, negative on error
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*/
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ssize_t lineread_get(struct lineread *lr, char **line)
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{
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bool eof = false;
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ssize_t line_len;
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while ((line_len = peek_line(lr, eof)) < 0) {
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ssize_t rc;
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if ((lr->next_line + lr->count) == LINEREAD_BUFFER_SIZE) {
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/* No space at end */
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if (lr->next_line == 0) {
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/* Buffer is full, which means we've
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* hit a line too long for us to
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* process. FIXME: report error
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* better
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*/
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return -1;
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}
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memmove(lr->buf, lr->buf + lr->next_line, lr->count);
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lr->next_line = 0;
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}
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/* Read more data into the end of buffer */
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rc = read(lr->fd, lr->buf + lr->next_line + lr->count,
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LINEREAD_BUFFER_SIZE - lr->next_line - lr->count);
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if (rc < 0)
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return rc;
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if (rc == 0)
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eof = true;
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else
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lr->count += rc;
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}
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*line = lr->buf + lr->next_line;
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lr->next_line += line_len;
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lr->count -= line_len;
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return line_len;
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}
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