projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| d310bb81 C |
1 | /* which.c: check to see if a file is executable. |
| 2 | ||
| 3 | This function was originally written with Maarten Litmaath's which.c as | |
| 4 | a template, but was changed in order to accomodate the possibility of | |
| 5 | rc's running setuid or the possibility of executing files not in the | |
| 6 | primary group. Much of this file has been re-vamped by Paul Haahr. | |
| 7 | I re-re-vamped the functions that Paul supplied to correct minor bugs | |
| 8 | and to strip out unneeded functionality. | |
| 9 | */ | |
| 10 | ||
| 11 | #include <sys/types.h> | |
| 12 | #include <sys/stat.h> | |
| 13 | #include <sys/param.h> | |
| 14 | #include <errno.h> | |
| 15 | #include "rc.h" | |
| 16 | ||
| 17 | #define X_USR 0100 | |
| 18 | #define X_GRP 0010 | |
| 19 | #define X_OTH 0001 | |
| 20 | #define X_ALL (X_USR|X_GRP|X_OTH) | |
| 21 | ||
| 22 | extern int stat(const char *, struct stat *); | |
| 23 | ||
| 24 | static bool initialized = FALSE; | |
| 25 | static int uid, gid; | |
| 26 | ||
| 27 | static int ngroups, gidset[NGROUPS]; | |
| 28 | ||
| 29 | /* determine whether gid lies in gidset */ | |
| 30 | ||
| 31 | static int ingidset(int g) { | |
| 32 | int i; | |
| 33 | for (i = 0; i < ngroups; i++) | |
| 34 | if (g == gidset[i]) | |
| 35 | return 1; | |
| 36 | return 0; | |
| 37 | } | |
| 38 | ||
| 39 | /* | |
| 40 | A home-grown access/stat. Does the right thing for group-executable files. | |
| 41 | Returns a bool instead of this -1 nonsense. | |
| 42 | */ | |
| 43 | ||
| 44 | static bool rc_access(char *path, bool verbose) { | |
| 45 | struct stat st; | |
| 46 | int mask; | |
| 47 | if (stat(path, &st) != 0) { | |
| 48 | if (verbose) /* verbose flag only set for absolute pathname */ | |
| 49 | uerror(path); | |
| 50 | return FALSE; | |
| 51 | } | |
| 52 | if (uid == 0) | |
| 53 | mask = X_ALL; | |
| 54 | else if (uid == st.st_uid) | |
| 55 | mask = X_USR; | |
| 56 | else if (gid == st.st_gid || ingidset(st.st_gid)) | |
| 57 | mask = X_GRP; | |
| 58 | else | |
| 59 | mask = X_OTH; | |
| 60 | if (((st.st_mode & S_IFMT) == S_IFREG) && (st.st_mode & mask)) | |
| 61 | return TRUE; | |
| 62 | errno = EACCES; | |
| 63 | if (verbose) | |
| 64 | uerror(path); | |
| 65 | return FALSE; | |
| 66 | } | |
| 67 | ||
| 68 | /* return a full pathname by searching $path, and by checking the status of the file */ | |
| 69 | ||
| 70 | extern char *which(char *name, bool verbose) { | |
| 71 | static char *test = NULL; | |
| 72 | static size_t testlen = 0; | |
| 73 | List *path; | |
| 74 | int len; | |
| 75 | if (name == NULL) /* no filename? can happen with "> foo" as a command */ | |
| 76 | return NULL; | |
| 77 | if (!initialized) { | |
| 78 | initialized = TRUE; | |
| 79 | uid = geteuid(); | |
| 80 | gid = getegid(); | |
| 81 | ngroups = getgroups(NGROUPS, gidset); | |
| 82 | } | |
| 83 | if (isabsolute(name)) /* absolute pathname? */ | |
| 84 | return rc_access(name, verbose) ? name : NULL; | |
| 85 | len = strlen(name); | |
| 86 | for (path = varlookup("path"); path != NULL; path = path->n) { | |
| 87 | size_t need = strlen(path->w) + len + 2; /* one for null terminator, one for the '/' */ | |
| 88 | if (testlen < need) { | |
| 89 | efree(test); | |
| 90 | test = ealloc(testlen = need); | |
| 91 | } | |
| 92 | if (*path->w == '\0') { | |
| 93 | strcpy(test, name); | |
| 94 | } else { | |
| 95 | strcpy(test, path->w); | |
| 96 | if (!streq(test, "/")) /* "//" is special to POSIX */ | |
| 97 | strcat(test, "/"); | |
| 98 | strcat(test, name); | |
| 99 | } | |
| 100 | if (rc_access(test, FALSE)) | |
| 101 | return test; | |
| 102 | } | |
| 103 | if (verbose) | |
| 104 | fprint(2, "%s not found\n", name); | |
| 105 | return NULL; | |
| 106 | } |