From a79b453de1772bf2b94b16259c8cdfa7fc587dbe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fabian=20Bl=C3=A4se?= <fabian@blaese.de>
Date: Fri, 8 Jan 2021 19:02:25 +0100
Subject: [PATCH] fff-random: Use strtol to parse numbers
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Other than atoi, strtol allows to detect parsing errors.
Therefore atoi is replaced with strtol and appropriate error
checks are added.

Fixes: #33 (gitea)

Signed-off-by: Fabian Bläse <fabian@blaese.de>
Reviewed-by: Johannes Kimmel <fff@bareminimum.eu>
---
 src/packages/fff/fff-random/Makefile     |  2 +-
 src/packages/fff/fff-random/src/random.c | 34 ++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/packages/fff/fff-random/Makefile b/src/packages/fff/fff-random/Makefile
index e862505f..456c0cb2 100644
--- a/src/packages/fff/fff-random/Makefile
+++ b/src/packages/fff/fff-random/Makefile
@@ -1,7 +1,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=fff-random
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)
 
diff --git a/src/packages/fff/fff-random/src/random.c b/src/packages/fff/fff-random/src/random.c
index 5d38d162..0f2013bb 100644
--- a/src/packages/fff/fff-random/src/random.c
+++ b/src/packages/fff/fff-random/src/random.c
@@ -6,6 +6,36 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <errno.h>
+
+static int parse_int(char *str) {
+        char *endptr = NULL;
+        errno = 0;
+        long val = strtol(str, &endptr, 10);
+
+        if (errno != 0) {
+                perror("strtol");
+                exit(EXIT_FAILURE);
+        }
+
+        if (endptr == str) {
+                fprintf(stderr, "No digits were found\n");
+                exit(EXIT_FAILURE);
+        }
+
+        if (*endptr != '\0') {
+                fprintf(stderr, "Further characters were found after number: \"%s\"\n", endptr);
+                exit(EXIT_FAILURE);
+        }
+
+        int retVal = (int) val;
+        if (val != retVal) {
+                fprintf(stderr, "Given number is out of range\n");
+                exit(EXIT_FAILURE);
+        }
+
+        return retVal;
+}
 
 int main(int argc, char **argv)
 {
@@ -22,8 +52,8 @@ int main(int argc, char **argv)
         }
         else if (argc == 3)
         {
-                from = atoi(argv[1]);
-                to = atoi(argv[2]);
+                from = parse_int(argv[1]);
+                to = parse_int(argv[2]);
         }
 
         diff = to - from;