Create new fgrepx common function

It's also slightly quicker.

src/claim.cgi.c

@@ -7,20 +7,6 @@
 char const *tokenlog = "/var/lib/ctf/tokend/tokens.log";
 char const *claimlog = "/var/lib/ctf/tokend/claim.log";
 
-int
-mystrcmp(char *a, char *b)
-{
-  while (*a == *b) {
-    a += 1;
-    b += 1;
-  }
-  if (((*a == '\0') || (*a == '\n')) &&
-      ((*b == '\0') || (*b == '\n'))) {
-    return 0;
-  }
-  return -1;
-}
-
 int
 main(int argc, char *argv[])
 {
@@ -75,31 +61,9 @@ main(int argc, char *argv[])
     cgi_page("No such team", "");
   }
 
-  /* Does the token exist? */
-  {
-    FILE *f;
-    int   valid = 0;
-
-    f = fopen(claimlog, "r");
-    if (f) {
-      while (1) {
-        char line[100];
-
-        if (NULL == fgets(line, sizeof(line), f)) {
-          break;
-        }
-        if (0 == mystrcmp(line, token)) {
-          valid = 1;
-          break;
-        }
-      }
-      fclose(f);
-    }
-
-    if (! valid) {
-      cgi_page("Invalid token",
-               "<p>Sorry, that token's no good.</p>");
-    }
+  if (! fgrepx(token, claimlog)) {
+    cgi_page("Invalid token",
+             "<p>Sorry, that token's no good.</p>");
   }
 
   /* If the token's unclaimed, award points and log the claim */

src/common.c

@@ -7,6 +7,44 @@
 #include <time.h>
 #include "common.h"
 
+#define EOL(c) ((EOF == (c)) || (0 == (c)) || ('\n' == (c)))
+
+int
+fgrepx(char const *needle, char const *filename)
+{
+  FILE       *f;
+  int         found = 0;
+  char const *p     = needle;
+
+  f = fopen(filename, "r");
+  if (f) {
+    while (1) {
+      int c = fgetc(f);
+
+      /* This list of cases would have looked so much nicer in OCaml.  I
+         apologize. */
+      if (EOL(c) && (0 == *p)) {
+        found = 1;
+        break;
+      } else if (EOF == c) {
+        break;
+      } else if ((0 == p) || (*p != c)) {
+        p = needle;
+        do {
+          c = fgetc(f);
+        } while (! EOL(c));
+      } else if ('\n' == c) {
+        p = needle;
+      } else {
+        p += 1;
+      }
+    }
+    fclose(f);
+  }
+
+  return found;
+}
+
 int
 team_exists(char *teamhash)
 {

src/common.h

@@ -6,5 +6,6 @@
 
 int team_exists(char *teamhash);
 int award_points(char *teamhash, char *category, int point);
+int fgrepx(char const *needle, char const *filename);
 
 #endif