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authorRich Felker <dalias@aerifal.cx>2011-04-17 17:32:36 -0400
committerRich Felker <dalias@aerifal.cx>2011-04-17 17:32:36 -0400
commite98bdca9df8df791fe93ec8eec920fa8d14da1f5 (patch)
treea3cd1fc61d5f51911a2f67981dbd552ce42e73c9 /src
parent2afed79f15a32e9616a27f9d327cef0cefbbaab1 (diff)
downloadmusl-e98bdca9df8df791fe93ec8eec920fa8d14da1f5.tar.gz
minimal realpath implementation using /proc
clean and simple, but fails when the caller does not have permissions to open the file for reading or when /proc is not available. i may replace this with a full implementation later, possibly leaving this version as an optimization to use when it works.
Diffstat (limited to 'src')
-rw-r--r--src/misc/realpath.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/src/misc/realpath.c b/src/misc/realpath.c
index f6b55495..8dcf5ec9 100644
--- a/src/misc/realpath.c
+++ b/src/misc/realpath.c
@@ -1,6 +1,49 @@
#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
char *realpath(const char *filename, char *resolved)
{
+ int fd;
+ ssize_t r;
+ struct stat st1, st2;
+ char buf[15+3*sizeof(int)];
+ int alloc = 0;
+
+ if (!filename) {
+ errno = EINVAL;
+ return 0;
+ }
+
+ if (!resolved) {
+ alloc = 1;
+ resolved = malloc(PATH_MAX);
+ if (!resolved) return 0;
+ }
+
+ fd = open(filename, O_RDONLY|O_NONBLOCK);
+ if (fd < 0) return 0;
+ snprintf(buf, sizeof buf, "/proc/self/fd/%d", fd);
+
+ r = readlink(buf, resolved, PATH_MAX-1);
+ if (r < 0) goto err;
+ resolved[r] = 0;
+
+ fstat(fd, &st1);
+ r = stat(resolved, &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;
+err:
+ if (alloc) free(resolved);
+ close(fd);
return 0;
}