posix: signal: implement strsignal

Implementation and ztest for strsignal.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>

doc/services/portability/posix.rst

@@ -385,7 +385,8 @@ required for error and event handling.
     sigpending(),
     sigprocmask(),
     igsuspend(),
-    sigwait()
+    sigwait(),
+    strsignal(),yes
 
 .. csv-table:: POSIX_SPIN_LOCKS
    :header: API, Supported

include/zephyr/posix/signal.h

@@ -55,6 +55,7 @@ typedef struct {
 	unsigned long sig[DIV_ROUND_UP(_NSIG, BITS_PER_LONG)];
 } sigset_t;
 
+char *strsignal(int signum);
 int sigemptyset(sigset_t *set);
 int sigfillset(sigset_t *set);
 int sigaddset(sigset_t *set, int signo);

lib/posix/CMakeLists.txt

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
+set(GEN_DIR ${ZEPHYR_BINARY_DIR}/include/generated)
+
 zephyr_syscall_header(
   ${ZEPHYR_BASE}/include/zephyr/posix/time.h
 )
@@ -10,6 +12,20 @@ if(CONFIG_POSIX_API)
   zephyr_include_directories(${ZEPHYR_BASE}/include/zephyr/posix)
 endif()
 
+if(CONFIG_POSIX_SIGNAL)
+  set(STRSIGNAL_TABLE_H ${GEN_DIR}/posix/strsignal_table.h)
+
+  add_custom_command(
+    OUTPUT ${STRSIGNAL_TABLE_H}
+    COMMAND
+    ${PYTHON_EXECUTABLE}
+    ${ZEPHYR_BASE}/scripts/build/gen_strsignal_table.py
+    -i ${ZEPHYR_BASE}/include/zephyr/posix/signal.h
+    -o ${STRSIGNAL_TABLE_H}
+    DEPENDS ${ZEPHYR_BASE}/include/zephyr/posix/signal.h
+  )
+endif()
+
 if(CONFIG_POSIX_API OR CONFIG_PTHREAD_IPC OR CONFIG_POSIX_CLOCK OR
   CONFIG_POSIX_MQUEUE OR CONFIG_POSIX_FS OR CONFIG_EVENTFD OR CONFIG_GETOPT)
   # This is a temporary workaround so that Newlib declares the appropriate
@@ -29,7 +45,7 @@ zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK sleep.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK timer.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_FS fs.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MQUEUE mqueue.c)
-zephyr_library_sources_ifdef(CONFIG_POSIX_SIGNAL signal.c)
+zephyr_library_sources_ifdef(CONFIG_POSIX_SIGNAL signal.c ${STRSIGNAL_TABLE_H})
 zephyr_library_sources_ifdef(CONFIG_POSIX_UNAME uname.c)
 zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC _common.c)
 zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC barrier.c)

lib/posix/Kconfig.signal

@@ -16,4 +16,11 @@ config POSIX_RTSIG_MAX
 	  Define the maximum number of realtime signals (RTSIG_MAX).
 	  The range of realtime signals is [SIGRTMIN .. (SIGRTMIN+RTSIG_MAX)]
 
+config POSIX_SIGNAL_STRING_DESC
+	bool "Use full description for the strsignal API"
+	default y
+	help
+	  Use full description for the strsignal API.
+	  Will use 256 bytes of ROM.
+
 endif

lib/posix/signal.c

@@ -3,7 +3,10 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
+#include "posix/strsignal_table.h"
+
 #include <errno.h>
+#include <stdio.h>
 
 #include <zephyr/posix/signal.h>
 
@@ -68,3 +71,28 @@ int sigismember(const sigset_t *set, int signo)
 
 	return 1 & (set->sig[SIGNO_WORD_IDX(signo)] >> SIGNO_WORD_BIT(signo));
 }
+
+char *strsignal(int signum)
+{
+	static char buf[sizeof("RT signal " STRINGIFY(SIGRTMAX))];
+
+	if (!signo_valid(signum)) {
+		errno = EINVAL;
+		return "Invalid signal";
+	}
+
+	if (signo_is_rt(signum)) {
+		snprintf(buf, sizeof(buf), "RT signal %d", signum - SIGRTMIN);
+		return buf;
+	}
+
+	if (IS_ENABLED(CONFIG_POSIX_SIGNAL_STRING_DESC)) {
+		if (strsignal_list[signum] != NULL) {
+			return (char *)strsignal_list[signum];
+		}
+	}
+
+	snprintf(buf, sizeof(buf), "Signal %d", signum);
+
+	return buf;
+}

scripts/build/gen_strsignal_table.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2023 Meta
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+import os
+import re
+
+
+def front_matter():
+    return f'''
+/*
+ * This file is generated by {__file__}
+ */
+
+#include <zephyr/posix/signal.h>
+'''
+
+
+def gen_strsignal_table(input, output):
+    with open(input, 'r') as inf:
+
+        highest_signo = 0
+        symbols = []
+        msgs = {}
+
+        for line in inf.readlines():
+            # Select items of the form below (note: SIGNO is numeric)
+            # #define SYMBOL SIGNO /**< MSG */
+            pat = r'^#define[\s]+(SIG[A-Z_]*)[\s]+([1-9][0-9]*)[\s]+/\*\*<[\s]+(.*)[\s]+\*/[\s]*$'
+            match = re.match(pat, line)
+
+            if not match:
+                continue
+
+            symbol = match[1]
+            signo = int(match[2])
+            msg = match[3]
+
+            symbols.append(symbol)
+            msgs[symbol] = msg
+
+            highest_signo = max(int(signo), highest_signo)
+
+        try:
+            os.makedirs(os.path.dirname(output))
+        except BaseException:
+            # directory already present
+            pass
+
+        with open(output, 'w') as outf:
+
+            print(front_matter(), file=outf)
+
+            # Generate string table
+            print(
+                f'static const char *const strsignal_list[{highest_signo + 1}] = {{', file=outf)
+            for symbol in symbols:
+                print(f'\t[{symbol}] = "{msgs[symbol]}",', file=outf)
+
+            print('};', file=outf)
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(allow_abbrev=False)
+    parser.add_argument(
+        '-i',
+        '--input',
+        dest='input',
+        required=True,
+        help='input file (e.g. include/zephyr/posix/signal.h)')
+    parser.add_argument(
+        '-o',
+        '--output',
+        dest='output',
+        required=True,
+        help='output file (e.g. build/zephyr/misc/generated/lib/posix/strsignal_table.h)')
+
+    args = parser.parse_args()
+
+    return args
+
+
+def main():
+    args = parse_args()
+    gen_strsignal_table(args.input, args.output)
+
+
+if __name__ == '__main__':
+    main()

tests/posix/common/src/signal.c

@@ -6,6 +6,7 @@
 
 #include <errno.h>
 #include <signal.h>
+#include <stdio.h>
 
 #include <zephyr/kernel.h>
 #include <zephyr/ztest.h>
@@ -192,3 +193,26 @@ ZTEST(posix_apis, test_signal_ismember)
 	zassert_equal(sigismember(&set, SIGKILL), 0, "%s not expected to be member", "SIGKILL");
 	zassert_equal(sigismember(&set, SIGTERM), 0, "%s not expected to be member", "SIGTERM");
 }
+
+ZTEST(posix_apis, test_signal_strsignal)
+{
+	char buf[sizeof("RT signal " STRINGIFY(SIGRTMAX))] = {0};
+
+	zassert_mem_equal(strsignal(-1), "Invalid signal", sizeof("Invalid signal"));
+	zassert_mem_equal(strsignal(0), "Invalid signal", sizeof("Invalid signal"));
+	zassert_mem_equal(strsignal(_NSIG), "Invalid signal", sizeof("Invalid signal"));
+
+	zassert_mem_equal(strsignal(30), "Signal 30", sizeof("Signal 30"));
+	snprintf(buf, sizeof(buf), "RT signal %d", SIGRTMIN - SIGRTMIN);
+	zassert_mem_equal(strsignal(SIGRTMIN), buf, strlen(buf));
+	snprintf(buf, sizeof(buf), "RT signal %d", SIGRTMAX - SIGRTMIN);
+	zassert_mem_equal(strsignal(SIGRTMAX), buf, strlen(buf));
+
+#ifdef CONFIG_POSIX_SIGNAL_STRING_DESC
+	zassert_mem_equal(strsignal(SIGHUP), "Hangup", sizeof("Hangup"));
+	zassert_mem_equal(strsignal(SIGSYS), "Bad system call", sizeof("Bad system call"));
+#else
+	zassert_mem_equal(strsignal(SIGHUP), "Signal 1", sizeof("Signal 1"));
+	zassert_mem_equal(strsignal(SIGSYS), "Signal 31", sizeof("Signal 31"));
+#endif
+}

tests/posix/common/testcase.yaml

@@ -80,3 +80,6 @@ tests:
       - CONFIG_SPIN_VALIDATE=n
     integration_platforms:
       - mps2_an385
+  portability.posix.common.signal.strsignal_no_desc:
+    extra_configs:
+      - CONFIG_POSIX_SIGNAL_STRING_DESC=n

tests/posix/headers/src/signal_h.c

@@ -163,6 +163,7 @@ ZTEST(posix_headers, test_signal_h)
 	zassert_not_null(sigaddset);
 	zassert_not_null(sigdelset);
 	zassert_not_null(sigismember);
+	zassert_not_null(strsignal);
 #endif /* CONFIG_POSIX_SIGNAL */
 
 	if (IS_ENABLED(CONFIG_POSIX_API)) {