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/* access.c -- access testing and path searching ($Revision: 1.2 $) */
#define REQUIRE_STAT 1
#define REQUIRE_PARAM 1
#include "es.h"
#include "prim.h"
#define READ 4
#define WRITE 2
#define EXEC 1
#define USER 6
#define GROUP 3
#define OTHER 0
/* ingroupset -- determine whether gid lies in the user's set of groups */
static Boolean ingroupset(int gid) {
#ifdef NGROUPS
int i;
static int ngroups;
static gidset_t gidset[NGROUPS];
static Boolean initialized = FALSE;
if (!initialized) {
initialized = TRUE;
ngroups = getgroups(NGROUPS, gidset);
}
for (i = 0; i < ngroups; i++)
if (gid == gidset[i])
return TRUE;
#endif
return FALSE;
}
static int testperm(struct stat *stat, int perm) {
int mask;
static int uid, gid;
static Boolean initialized = FALSE;
if (perm == 0)
return 0;
if (!initialized) {
initialized = TRUE;
uid = geteuid();
gid = getegid();
}
mask = (uid == 0)
? (perm << USER) | (perm << GROUP) | (perm << OTHER)
: (perm <<
((uid == stat->st_uid)
? USER
: ((gid == stat->st_gid || ingroupset(stat->st_gid))
? GROUP
: OTHER)));
return (stat->st_mode & mask) ? 0 : EACCES;
}
static int testfile(char *path, int perm, int type) {
struct stat st;
#ifdef S_IFLNK
if (type == S_IFLNK) {
if (lstat(path, &st) == -1)
return errno;
} else
#endif
if (stat(path, &st) == -1)
return errno;
if (type != 0 && (st.st_mode & S_IFMT) != type)
return EACCES; /* what is an appropriate return value? */
return testperm(&st, perm);
}
static char *pathcat(char *prefix, char *suffix) {
char *s;
size_t plen, slen, len;
static char *pathbuf = NULL;
static size_t pathlen = 0;
if (*prefix == '\0')
return suffix;
if (*suffix == '\0')
return prefix;
plen = strlen(prefix);
slen = strlen(suffix);
len = plen + slen + 2; /* one for '/', one for '\0' */
if (pathlen < len) {
pathlen = len;
pathbuf = erealloc(pathbuf, pathlen);
}
memcpy(pathbuf, prefix, plen);
s = pathbuf + plen;
if (s[-1] != '/')
*s++ = '/';
memcpy(s, suffix, slen + 1);
return pathbuf;
}
PRIM(access) {
int c, perm = 0, type = 0, estatus = ENOENT;
Boolean first = FALSE, exception = FALSE;
char *suffix = NULL;
List *lp;
const char * const usage = "access [-n name] [-1e] [-rwx] [-fdcblsp] path ...";
gcdisable();
esoptbegin(list, "$&access", usage);
while ((c = esopt("bcdefln:prswx1")) != EOF)
switch (c) {
case 'n': suffix = getstr(esoptarg()); break;
case '1': first = TRUE; break;
case 'e': exception = TRUE; break;
case 'r': perm |= READ; break;
case 'w': perm |= WRITE; break;
case 'x': perm |= EXEC; break;
case 'f': type = S_IFREG; break;
case 'd': type = S_IFDIR; break;
case 'c': type = S_IFCHR; break;
case 'b': type = S_IFBLK; break;
#ifdef S_IFLNK
case 'l': type = S_IFLNK; break;
#endif
#ifdef S_IFSOCK
case 's': type = S_IFSOCK; break;
#endif
#ifdef S_IFIFO
case 'p': type = S_IFIFO; break;
#endif
default:
esoptend();
fail("$&access", "access -%c is not supported on this system", c);
}
list = esoptend();
for (lp = NULL; list != NULL; list = list->next) {
int error;
char *name;
name = getstr(list->term);
if (suffix != NULL)
name = pathcat(name, suffix);
error = testfile(name, perm, type);
if (first) {
if (error == 0) {
Ref(List *, result,
mklist(mkstr(suffix == NULL
? name
: gcdup(name)),
NULL));
gcenable();
RefReturn(result);
} else if (error != ENOENT)
estatus = error;
} else
lp = mklist(mkstr(error == 0 ? "0" : esstrerror(error)),
lp);
}
if (first && exception) {
gcenable();
if (suffix)
fail("$&access", "%s: %s", suffix, esstrerror(estatus));
else
fail("$&access", "%s", esstrerror(estatus));
}
Ref(List *, result, reverse(lp));
gcenable();
RefReturn(result);
}
extern Dict *initprims_access(Dict *primdict) {
X(access);
return primdict;
}
extern char *checkexecutable(char *file) {
int err = testfile(file, EXEC, S_IFREG);
return err == 0 ? NULL : esstrerror(err);
}
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