#include <stdlib.h> #include <errno.h> #include <sys/stat.h> #include <dirent.h> #include <string.h> /* These functions find the absolute path to the current working directory. */ static char *recurser(); /* Routine to go up tree */ static char *search_dir(); /* Routine to find the step back down */ static char *path_buf; static int path_size; static dev_t root_dev; static ino_t root_ino; static struct stat st; char *getcwd( char *buf, int size) { path_size = size; if (size < 3) { errno = ERANGE; return NULL; } if (buf != NULL) path_buf = buf; else { path_buf = malloc (size); if (path_buf == NULL) return NULL; } strcpy(path_buf, "."); if (stat("/", &st) < 0) return NULL; root_dev = st.st_dev; root_ino = st.st_ino; return recurser(); } static char *recurser() { dev_t this_dev; ino_t this_ino; if (stat(path_buf, &st) < 0) return 0; this_dev = st.st_dev; this_ino = st.st_ino; if (this_dev == root_dev && this_ino == root_ino) { strcpy(path_buf, "/"); return path_buf; } if (strlen(path_buf) + 4 > path_size) { errno = ERANGE; return 0; } strcat(path_buf, "/.."); if (recurser() == 0) return 0; return search_dir(this_dev, this_ino); } static char *search_dir(this_dev, this_ino) dev_t this_dev; ino_t this_ino; { DIR *dp; struct dirent *d; char *ptr; int slen; /* The test is for ELKS lib 0.0.9, this should be fixed in the real kernel */ int slow_search = (sizeof(ino_t) != sizeof(d->d_ino)); if (stat(path_buf, &st) < 0) return 0; if (this_dev != st.st_dev) slow_search = 1; slen = strlen(path_buf); ptr = path_buf + slen - 1; if (*ptr != '/') { if (slen + 2 > path_size) { errno = ERANGE; return 0; } strcpy(++ptr, "/"); slen++; } slen++; dp = opendir(path_buf); if (dp == 0) return 0; while ((d = readdir(dp)) != 0) { if (slow_search || this_ino == d->d_ino) { if (slen + strlen(d->d_name) > path_size) { errno = ERANGE; return 0; } strcpy(ptr + 1, d->d_name); if (stat(path_buf, &st) < 0) continue; if (st.st_ino == this_ino && st.st_dev == this_dev) { closedir(dp); return path_buf; } } } closedir(dp); errno = ENOENT; return 0; }