src/can_user_push_http.c

   1 /*
   2
   3 can_user_push_http.c -- check project membership in group file
   4 Copyright (c) 2014 Kyle J. McKay.  All rights reserved.
   5
   6 This program is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU General Public License
   8 as published by the Free Software Foundation; either version 2
   9 of the License, or (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  19
  20 */
  21
  22 /*
  23   USAGE: can_user_push_http groupname username
  24   Exit code 0 for yes, non-zero for no
  25   If username is an explicit member of groupname returns yes
  26   Wrong number of or bad arguments exits with non-zero
  27   Directly reads compiled in GROUP_FILE location
  28 */
  29
  30 #ifndef GROUP_FILE
  31 #error GROUP_FILE must be defined to a string which is the full pathname to\
  32  the /etc/group format file to read
  33 #endif
  34
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <stdio.h>
  38
  39 #define BADCHARS ":,# \t\r\n"
  40 #define MAX_LINE_SIZE 16384 /* includes trailing \n and \0 */
  41 #define MAX_NAME_LEN 64
  42
  43 static char linebuffer[MAX_LINE_SIZE];
  44 static char membersearch[1+MAX_NAME_LEN+1+1];
  45
  46 int is_valid_name(const char *name)
  47 {
  48   size_t len;
  49
  50   if (!name || !*name)
  51     return 0;
  52   len = strlen(name);
  53   if (len > MAX_NAME_LEN || strcspn(name, BADCHARS) != len)
  54     return 0;
  55   return 1;
  56 }
  57
  58 int main(int argc, char *argv[])
  59 {
  60   FILE *groupfile;
  61   size_t len;
  62
  63   if (argc != 3)
  64     return EXIT_FAILURE;
  65   if (!is_valid_name(argv[1]) || !is_valid_name(argv[2]))
  66     return EXIT_FAILURE;
  67
  68   len = strlen(argv[2]);
  69   membersearch[0] = ',';
  70   strncpy(membersearch+1, argv[2], len);
  71   membersearch[len+1] = ',';
  72   membersearch[len+2] = '\0';
  73
  74   groupfile = fopen(GROUP_FILE, "r");
  75   if (!groupfile)
  76     return EXIT_FAILURE;
  77   while (fgets(linebuffer, sizeof(linebuffer)-1, groupfile)) {
  78     char *trimmed, *members;
  79     size_t len = strlen(linebuffer);
  80
  81     if (len >= sizeof(linebuffer) - 2)
  82       return EXIT_FAILURE;
  83     if (len && linebuffer[len-1] == '\n')
  84       linebuffer[--len] = '\0';
  85     trimmed = linebuffer + strspn(linebuffer, " \t");
  86     if (!*trimmed || *trimmed == '#')
  87       continue;
  88     if (trimmed != linebuffer)
  89       return EXIT_FAILURE;
  90     trimmed = strchr(linebuffer, ':');
  91     if (!trimmed)
  92       return EXIT_FAILURE;
  93     *trimmed = '\0';
  94     if (strcmp(linebuffer, argv[1]))
  95       continue; /* not the group we're looking for */
  96     trimmed = strchr(trimmed + 1, ':');
  97     if (!trimmed)
  98       return EXIT_FAILURE;
  99     trimmed = strchr(trimmed + 1, ':');
 100     if (!trimmed)
 101       return EXIT_FAILURE;
 102     *trimmed = ',';
 103     members = trimmed;
 104     trimmed = strchr(trimmed + 1, ':');
 105     if (!trimmed)
 106       trimmed = linebuffer + len;
 107     *trimmed++ = ',';
 108     *trimmed = '\0';
 109     return strstr(members, membersearch) ? EXIT_SUCCESS : EXIT_FAILURE;
 110   }
 111   return EXIT_FAILURE;
 112 }