mirror of
https://passt.top/passt
synced 2024-11-05 20:31:11 +00:00
dab2c6ee1f
Two places in passt need to read files line by line (one parsing resolv.conf, the other parsing /proc/net/*. They can't use fgets() because in glibc that can allocate memory. Instead they use an implementation line_read() in util.c. This has some problems: * It has two completely separate modes of operation, one buffering and one not, the relation between these and how they're activated is subtle and confusing * At least in non-buffered mode, it will mishandle an empty line, folding them onto the start of the next non-empty line * In non-buffered mode it will use lseek() which prevents using this on non-regular files (we don't need that at present, but it's a surprising limitation) * It has a lot of difficult to read pointer mangling Add a new cleaner implementation of allocation-free line-by-line reading in lineread.c. This one always buffers, using a state structure to keep track of what we need. This is larger than I'd like, but it turns out handling all the edge cases of line-by-line reading in C is surprisingly hard. This just adds the code, subsequent patches will change the existing users of line_read() to the new implementation. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
32 lines
803 B
C
32 lines
803 B
C
/* SPDX-License-Identifier: AGPL-3.0-or-later
|
|
* Copyright Red Hat
|
|
* Author: David Gibson <david@gibson.dropbear.id.au>
|
|
*/
|
|
|
|
#ifndef LINEREAD_H
|
|
#define LINEREAD_H
|
|
|
|
#define LINEREAD_BUFFER_SIZE 8192
|
|
|
|
/**
|
|
* struct lineread - Line reader state
|
|
* @fd: File descriptor lines are read from
|
|
* @next_line: Offset in @buf of the start of the first line not yet
|
|
* returned by lineread_get()
|
|
* @count: Number of bytes in @buf read from the file, but not yet
|
|
* returned by lineread_get()
|
|
* @buf: Buffer storing data read from file.
|
|
*/
|
|
struct lineread {
|
|
int fd; int next_line;
|
|
int count;
|
|
|
|
/* One extra byte for possible trailing \0 */
|
|
char buf[LINEREAD_BUFFER_SIZE+1];
|
|
};
|
|
|
|
void lineread_init(struct lineread *lr, int fd);
|
|
int lineread_get(struct lineread *lr, char **line);
|
|
|
|
#endif /* _LINEREAD_H */
|