fatal-signal: Remove dependency upon xalloc

[Bruno Haible]

I need to use the module 'clean-temp' and, with it, the module 'fatal-signal'
in a library under GPLv2+ (namely, GNU libffcall). To this effect, functions
in this module should not call xalloc_die() (since that is under GPLv3+)
but instead return an error indicator.

This patch is the first part of the change.


2021-03-21  Bruno Haible  <bruno@clisp.org>

        fatal-signal: Remove dependency upon xalloc.
        * lib/fatal-signal.h (at_fatal_signal): Change return type to 'int'.
        * lib/fatal-signal.c: Don't include xalloc.h.
        (at_fatal_signal): Return an error indicator.
        * modules/fatal-signal (Depends-on): Remove xalloc.
        * NEWS: Mention the change.
        * lib/term-style-control.c: Include xalloc.h.
        (ensure_other_signal_handlers): Test return value of at_fatal_signal.
        * lib/clean-temp.c (do_init_clean_temp): Likewise.
        * lib/wait-process.c (register_slave_subprocess): Likewise.
        * modules/term-style-control (Depends-on): Add xalloc-die.
        * modules/clean-temp (Depends-on): Likewise.
        * modules/wait-process (Depends-on): Likewise.

diff --git a/NEWS b/NEWS
index 77cf565..98931a3 100644
--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,9 @@ User visible incompatible changes
 
 Date        Modules         Changes
 
+2021-03-21  fatal-signal    The function at_fatal_signal now returns an error
+                            indicator.
+
 2021-03-21  diacrit         This deprecated module is removed.
 
 2021-03-07  mbrtowc         For single-locale optimizations, you now need to
diff --git a/lib/clean-temp.c b/lib/clean-temp.c
index 885d5ab..268aa48 100644
--- a/lib/clean-temp.c
+++ b/lib/clean-temp.c
@@ -385,7 +385,8 @@ do_init_clean_temp (void)
   /* Initialize the data used by the cleanup handler.  */
   init_fatal_signal_set ();
   /* Register the cleanup handler.  */
-  at_fatal_signal (&cleanup_action);
+  if (at_fatal_signal (&cleanup_action) < 0)
+    xalloc_die ();
 }
 
 /* Ensure that do_init_clean_temp is called once only.  */
diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c
index 15aa522..ba5fb53 100644
--- a/lib/fatal-signal.c
+++ b/lib/fatal-signal.c
@@ -29,7 +29,6 @@
 #include "glthread/lock.h"
 #include "thread-optim.h"
 #include "sig-handler.h"
-#include "xalloc.h"
 
 #define SIZEOF(a) (sizeof(a) / sizeof(a[0]))
 
@@ -211,7 +210,7 @@ gl_lock_define_initialized (static, at_fatal_signal_lock)
 
 /* Register a cleanup function to be executed when a catchable fatal signal
    occurs.  */
-void
+int
 at_fatal_signal (action_t action)
 {
   bool mt = gl_multithreaded ();
@@ -226,6 +225,8 @@ at_fatal_signal (action_t action)
       cleanup_initialized = true;
     }
 
+  int ret = 0;
+
   if (actions_count == actions_allocated)
     {
       /* Extend the actions array.  Note that we cannot use xrealloc(),
@@ -235,9 +236,15 @@ at_fatal_signal (action_t action)
       size_t old_actions_allocated = actions_allocated;
       size_t new_actions_allocated = 2 * actions_allocated;
       actions_entry_t *new_actions =
-        XNMALLOC (new_actions_allocated, actions_entry_t);
-      size_t k;
+        (actions_entry_t *)
+        malloc (new_actions_allocated * sizeof (actions_entry_t));
+      if (new_actions == NULL)
+        {
+          ret = -1;
+          goto done;
+        }
 
+      size_t k;
       /* Don't use memcpy() here, because memcpy takes non-volatile arguments
          and is therefore not guaranteed to complete all memory stores before
          the next statement.  */
@@ -263,7 +270,10 @@ at_fatal_signal (action_t action)
   actions[actions_count].action = action;
   actions_count++;
 
+ done:
   if (mt) gl_lock_unlock (at_fatal_signal_lock);
+
+  return ret;
 }
 
 
diff --git a/lib/fatal-signal.h b/lib/fatal-signal.h
index 3bcf8a9..e8c69f1 100644
--- a/lib/fatal-signal.h
+++ b/lib/fatal-signal.h
@@ -56,8 +56,10 @@ extern "C" {
 
    The cleanup function is executed asynchronously.  It is unspecified
    whether during its execution the catchable fatal signals are blocked
-   or not.  */
-extern void at_fatal_signal (_GL_ASYNC_SAFE void (*function) (int sig));
+   or not.
+
+   Return 0 upon success, or -1 if there was a memory allocation problem.  */
+extern int at_fatal_signal (_GL_ASYNC_SAFE void (*function) (int sig));
 
 
 /* Sometimes it is necessary to block the usually fatal signals while the
diff --git a/lib/term-style-control.c b/lib/term-style-control.c
index 72099a3..d2d2133 100644
--- a/lib/term-style-control.c
+++ b/lib/term-style-control.c
@@ -46,6 +46,7 @@
 #include "sig-handler.h"
 #include "full-write.h"
 #include "same-inode.h"
+#include "xalloc.h"
 
 #define SIZEOF(a) (sizeof(a) / sizeof(a[0]))
 
@@ -813,7 +814,8 @@ ensure_other_signal_handlers (void)
   if (!signal_handlers_installed)
     {
       /* Install the handlers for the fatal signals.  */
-      at_fatal_signal (fatal_signal_handler);
+      if (at_fatal_signal (fatal_signal_handler) < 0)
+        xalloc_die ();
 
       #if defined SIGCONT
 
diff --git a/lib/wait-process.c b/lib/wait-process.c
index 88a1eaa..bbf5de2 100644
--- a/lib/wait-process.c
+++ b/lib/wait-process.c
@@ -121,7 +121,8 @@ register_slave_subprocess (pid_t child)
   if (!cleanup_slaves_registered)
     {
       atexit (cleanup_slaves);
-      at_fatal_signal (cleanup_slaves_action);
+      if (at_fatal_signal (cleanup_slaves_action) < 0)
+        xalloc_die ();
       cleanup_slaves_registered = true;
     }
 
diff --git a/modules/clean-temp b/modules/clean-temp
index 8551ce5..2eca006 100644
--- a/modules/clean-temp
+++ b/modules/clean-temp
@@ -21,6 +21,7 @@ tmpdir
 mkdtemp
 rmdir
 xalloc
+xalloc-die
 xmalloca
 linkedhash-list
 linked-list
diff --git a/modules/fatal-signal b/modules/fatal-signal
index c56956c..d3bb099 100644
--- a/modules/fatal-signal
+++ b/modules/fatal-signal
@@ -9,7 +9,6 @@ m4/sig_atomic_t.m4
 
 Depends-on:
 c99
-xalloc
 stdbool
 unistd
 sigaction
diff --git a/modules/term-style-control b/modules/term-style-control
index a6fdd5b..85d748d 100644
--- a/modules/term-style-control
+++ b/modules/term-style-control
@@ -13,6 +13,7 @@ sigprocmask
 full-write
 fstat
 same-inode
+xalloc-die
 
 configure.ac:
 AC_REQUIRE([AC_C_INLINE])
diff --git a/modules/wait-process b/modules/wait-process
index 7ffe832..f727111 100644
--- a/modules/wait-process
+++ b/modules/wait-process
@@ -11,6 +11,7 @@ Depends-on:
 fatal-signal
 error
 xalloc
+xalloc-die
 gettext-h
 stdbool
 stdlib