busybox/libbb/xreadlink.c

/* vi: set sw=4 ts=4: */
/*
 *  xreadlink.c - safe implementation of readlink.
 *  Returns a NULL on failure...
 */

#include "libbb.h"

/*
 * NOTE: This function returns a malloced char* that you will have to free
 * yourself. You have been warned.
 */

char *xreadlink(const char *path)
{
	enum { GROWBY = 80 }; /* how large we will grow strings by */

	char *buf = NULL;
	int bufsize = 0, readsize = 0;

	do {
		buf = xrealloc(buf, bufsize += GROWBY);
		readsize = readlink(path, buf, bufsize); /* 1st try */
		if (readsize == -1) {
			bb_perror_msg("%s", path);
			free(buf);
			return NULL;
		}
	}
	while (bufsize < readsize + 1);

	buf[readsize] = '\0';

	return buf;
}

char *xmalloc_realpath(const char *path)
{
#if defined(__GLIBC__) && !defined(__UCLIBC__)
	/* glibc provides a non-standard extension */
	return realpath(path, NULL);
#else
	char buf[PATH_MAX+1];

	/* on error returns NULL (xstrdup(NULL) ==NULL) */
	return xstrdup(realpath(path, buf));
#endif
}
1	/* vi: set sw=4 ts=4: */
2	/*
3	* xreadlink.c - safe implementation of readlink.
4	* Returns a NULL on failure...
5	*/
6
7	#include "libbb.h"
8
9	/*
10	* NOTE: This function returns a malloced char* that you will have to free
11	* yourself. You have been warned.
12	*/
13
14	char xreadlink(const char path)
15	{
16	enum { GROWBY = 80 }; /* how large we will grow strings by */
17
18	char *buf = NULL;
19	int bufsize = 0, readsize = 0;
20
21	do {
22	buf = xrealloc(buf, bufsize += GROWBY);
23	readsize = readlink(path, buf, bufsize); /* 1st try */
24	if (readsize == -1) {
25	bb_perror_msg("%s", path);
26	free(buf);
27	return NULL;
28	}
29	}
30	while (bufsize < readsize + 1);
31
32	buf[readsize] = '\0';
33
34	return buf;
35	}
36
37	char xmalloc_realpath(const char path)
38	{
39	#if defined(__GLIBC__) && !defined(__UCLIBC__)
40	/* glibc provides a non-standard extension */
41	return realpath(path, NULL);
42	#else
43	char buf[PATH_MAX+1];
44
45	/* on error returns NULL (xstrdup(NULL) ==NULL) */
46	return xstrdup(realpath(path, buf));
47	#endif
48	}