From dfddd43256f7ad4bad991eeff5cc51772595f327 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 31 Aug 2013 15:50:23 -0400 Subject: [PATCH] debloat realpath's allocation strategy rather than allocating a PATH_MAX-sized buffer when the caller does not provide an output buffer, work first with a PATH_MAX-sized temp buffer with automatic storage, and either copy it to the caller's buffer or strdup it on success. this not only avoids massive memory waste, but also avoids pulling in free (and thus the full malloc implementation) unnecessarily in static programs. --- src/misc/realpath.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/src/misc/realpath.c b/src/misc/realpath.c index 2b846497..43d40183 100644 --- a/src/misc/realpath.c +++ b/src/misc/realpath.c @@ -5,6 +5,7 @@ #include #include #include +#include void __procfdname(char *, unsigned); @@ -14,7 +15,7 @@ char *realpath(const char *restrict filename, char *restrict resolved) ssize_t r; struct stat st1, st2; char buf[15+3*sizeof(int)]; - int alloc = 0; + char tmp[PATH_MAX]; if (!filename) { errno = EINVAL; @@ -25,27 +26,20 @@ char *realpath(const char *restrict filename, char *restrict resolved) if (fd < 0) return 0; __procfdname(buf, fd); - if (!resolved) { - alloc = 1; - resolved = malloc(PATH_MAX); - if (!resolved) return 0; - } - - r = readlink(buf, resolved, PATH_MAX-1); + r = readlink(buf, tmp, sizeof tmp - 1); if (r < 0) goto err; - resolved[r] = 0; + tmp[r] = 0; fstat(fd, &st1); - r = stat(resolved, &st2); + r = stat(tmp, &st2); if (r<0 || st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino) { if (!r) errno = ELOOP; goto err; } close(fd); - return resolved; + return resolved ? strcpy(resolved, tmp) : strdup(tmp); err: - if (alloc) free(resolved); close(fd); return 0; } -- GitLab