Simplify get_local_group to return the allocated buffer instead of copying.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

diff --git a/nonlocal-group.c b/nonlocal-group.c
index 085fafdb35a373255a002e9094d7ecb510fe2b67..3eb9fe9ba3c250c3388aa9cdc565a08ad3cc8b7f 100644 (file)
--- a/nonlocal-group.c
+++ b/nonlocal-group.c
@@ -127,7 +127,7 @@ check_nonlocal_gid(const char *user, gid_t gid, int *errnop)
 }
 
 enum nss_status
-get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen, int *errnop)
+get_local_group(const char *name, struct group *grp, char **buffer, int *errnop)
 {
     static const char *fct_name = "getgrnam_r";
     static service_user *startp = NULL;
@@ -139,13 +139,12 @@ get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen
                             char *buffer, size_t buflen, int *errnop);
        void *ptr;
     } fct;
-    struct group gbuf;
-    int n;
+    size_t buflen;
     int old_errno = errno;
 
-    int len = sysconf(_SC_GETGR_R_SIZE_MAX);
-    char *buf = malloc(len);
-    if (buf == NULL) {
+    buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+    *buffer = malloc(buflen);
+    if (*buffer == NULL) {
        *errnop = ENOMEM;
        errno = old_errno;
        return NSS_STATUS_TRYAGAIN;
@@ -153,7 +152,8 @@ get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen
 
     if (fct_start == NULL &&
        __nss_group_lookup(&startp, fct_name, &fct_start) != 0) {
-       free(buf);
+       free(*buffer);
+       *buffer = NULL;
        return NSS_STATUS_UNAVAIL;
     }
     nip = startp;
@@ -163,12 +163,12 @@ get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen
        if (fct.l == _nss_nonlocal_getgrnam_r)
            status = NSS_STATUS_NOTFOUND;
        else
-           status = DL_CALL_FCT(fct.l, (name, &gbuf, buf, len, errnop));
+           status = DL_CALL_FCT(fct.l, (name, grp, *buffer, buflen, errnop));
        if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) {
-           free(buf);
-           len *= 2;
-           buf = malloc(len);
-           if (buf == NULL) {
+           free(*buffer);
+           buflen *= 2;
+           *buffer = malloc(buflen);
+           if (*buffer == NULL) {
                *errnop = ENOMEM;
                errno = old_errno;
                return NSS_STATUS_TRYAGAIN;
@@ -177,42 +177,11 @@ get_local_group(const char *name, struct group *grp, char *buffer, size_t buflen
        }
     } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
 
-    if (status != NSS_STATUS_SUCCESS)
-       goto get_local_group_done;
-
-    n = snprintf(buffer, buflen, "%s", gbuf.gr_name);
-    if (n < 0 || n >= buflen) {
-       *errnop = ERANGE;
-       status = NSS_STATUS_TRYAGAIN;
-       goto get_local_group_done;
-    }
-    grp->gr_name = buffer;
-    buffer += n;
-    buflen -= n;
-
-    n = snprintf(buffer, buflen, "%s", gbuf.gr_passwd);
-    if (n < 0 || n >= buflen) {
-       *errnop = ERANGE;
-       status = NSS_STATUS_TRYAGAIN;
-       goto get_local_group_done;
-    }
-    grp->gr_passwd = buffer;
-    buffer += n;
-    buflen -= n;
-
-    grp->gr_gid = gbuf.gr_gid;
-
-    if (buflen < sizeof(void *)) {
-       *errnop = ERANGE;
-       status = NSS_STATUS_TRYAGAIN;
-       goto get_local_group_done;
+    if (status != NSS_STATUS_SUCCESS) {
+       free(*buffer);
+       *buffer = NULL;
     }
-    *(void **)buffer = NULL;
-    buffer += sizeof(void *);
-    buflen -= sizeof(void *);
 
- get_local_group_done:
-    free(buf);
     return status;
 }
 
@@ -420,7 +389,6 @@ _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start,
     struct group local_users_group, nonlocal_users_group;
     gid_t local_users_gid, gid;
     int is_local = 0;
-    int buflen;
     char *buffer;
 
     /* Check that the user is a nonlocal user before adding any groups. */
@@ -432,50 +400,34 @@ _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start,
 
     int old_errno = errno;
 
-    buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
-    buffer = malloc(buflen);
-    if (buffer == NULL) {
-       *errnop = ENOMEM;
-       errno = old_errno;
-       return NSS_STATUS_TRYAGAIN;
-    }
     status = get_local_group(MAGIC_LOCAL_GROUPNAME,
-                            &local_users_group, buffer, buflen, errnop);
+                            &local_users_group, &buffer, errnop);
     if (status == NSS_STATUS_SUCCESS) {
        local_users_gid = local_users_group.gr_gid;
-    } else if (status == NSS_STATUS_TRYAGAIN) {
        free(buffer);
+    } else if (status == NSS_STATUS_TRYAGAIN) {
        return status;
     } else {
        syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!",
               MAGIC_LOCAL_GROUPNAME);
        local_users_gid = -1;
     }
-    free(buffer);
 
     if (is_local) {
        gid = local_users_gid;
     } else {
-       buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
-       buffer = malloc(buflen);
-       if (buffer == NULL) {
-           *errnop = ENOMEM;
-           errno = old_errno;
-           return NSS_STATUS_TRYAGAIN;
-       }
        status = get_local_group(MAGIC_NONLOCAL_GROUPNAME,
-                                &nonlocal_users_group, buffer, buflen, errnop);
+                                &nonlocal_users_group, &buffer, errnop);
        if (status == NSS_STATUS_SUCCESS) {
            gid = nonlocal_users_group.gr_gid;
-       } else if (status == NSS_STATUS_TRYAGAIN) {
            free(buffer);
+       } else if (status == NSS_STATUS_TRYAGAIN) {
            return status;
        } else {
            syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!",
                   MAGIC_NONLOCAL_GROUPNAME);
            gid = -1;
        }
-       free(buffer);
     }
 
     if (gid != -1) {