1#include <stdlib.h> 2#include <limits.h> 3#include <sys/stat.h> 4#include <fcntl.h> 5#include <errno.h> 6#include <unistd.h> 7#include <string.h> 8#include "syscall.h" 9 10void __procfdname(char *, unsigned); 11 12char *realpath(const char *restrict filename, char *restrict resolved) 13{ 14 int fd; 15 ssize_t r; 16 struct stat st1, st2; 17 char buf[15+3*sizeof(int)]; 18 char tmp[PATH_MAX]; 19 20 if (!filename) { 21 errno = EINVAL; 22 return 0; 23 } 24 25 fd = sys_open(filename, O_PATH|O_NONBLOCK|O_CLOEXEC); 26 if (fd < 0) return 0; 27 __procfdname(buf, fd); 28 29 r = readlink(buf, tmp, sizeof tmp - 1); 30 if (r < 0) goto err; 31 tmp[r] = 0; 32 33 fstat(fd, &st1); 34 r = stat(tmp, &st2); 35 if (r<0 || st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino) { 36 if (!r) errno = ELOOP; 37 goto err; 38 } 39 40 __syscall(SYS_close, fd); 41 return resolved ? strcpy(resolved, tmp) : strdup(tmp); 42err: 43 __syscall(SYS_close, fd); 44 return 0; 45} 46