From 9f26b250bbc1d97f1093a0997bfd5ccc504a56b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Sat, 1 Jan 2022 21:11:31 +0100
Subject: [PATCH] foot{,client}: handle argc == 0
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Our getopt_long() based argument parser would (correctly) break out of
the while loop immediately. However, we would then proceed and
decrement ‘argc’ by 1, resulting in it being -1.

This was then passed to the terminal constructor, which passed it on
to the client application fork+exec logic. That finally resulted in an
exec(3) failure:

   err: slave.c:339: SHELL=/bin/zsh: failed to execute: No such file or directory
   err: fdm.c:215: no such FD: 7
  info: main.c:604: goodbye
---
 client.c | 8 +++++---
 main.c   | 8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/client.c b/client.c
index b6749835..df43e7d5 100644
--- a/client.c
+++ b/client.c
@@ -124,7 +124,7 @@ main(int argc, char *const *argv)
     static const int foot_exit_failure = -36;
     int ret = foot_exit_failure;
 
-    const char *const prog_name = argv[0];
+    const char *const prog_name = argc > 0 ? argv[0] : "<nullptr>";
 
     static const struct option longopts[] =  {
         {"term",               required_argument, NULL, 't'},
@@ -309,8 +309,10 @@ main(int argc, char *const *argv)
         }
     }
 
-    argc -= optind;
-    argv += optind;
+    if (argc > 0) {
+        argc -= optind;
+        argv += optind;
+    }
 
     log_init(log_colorize, false, LOG_FACILITY_USER, log_level);
 
diff --git a/main.c b/main.c
index 7370de29..34f72a7c 100644
--- a/main.c
+++ b/main.c
@@ -168,7 +168,7 @@ main(int argc, char *const *argv)
      * don't pass this on to programs launched by us */
     unsetenv("DESKTOP_STARTUP_ID");
 
-    const char *const prog_name = argv[0];
+    const char *const prog_name = argc > 0 ? argv[0] : "<nullptr>";
 
     static const struct option longopts[] =  {
         {"config",                 required_argument, NULL, 'c'},
@@ -401,8 +401,10 @@ main(int argc, char *const *argv)
         as_server && log_syslog,
         (enum fcft_log_class)log_level);
 
-    argc -= optind;
-    argv += optind;
+    if (argc > 0) {
+        argc -= optind;
+        argv += optind;
+    }
 
     LOG_INFO("%s", version_and_features());