libbb: reduce the overhead of single parameter bb_error_msg() calls

Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by
Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower
overhead call to bb_perror_msg() when only a string was being printed
with no parameters. This saves space for some CPU architectures because
it avoids the overhead of a call to a variadic function. However there
has never been a simple version of bb_error_msg(), and since 2007 many
new calls to bb_perror_msg() have been added that only take a single
parameter and so could have been using bb_simple_perror_message().

This changeset introduces 'simple' versions of bb_info_msg(),
bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and
bb_herror_msg_and_die(), and replaces all calls that only take a
single parameter, or use something like ("%s", arg), with calls to the
corresponding 'simple' version.

Since it is likely that single parameter calls to the variadic functions
may be accidentally reintroduced in the future a new debugging config
option WARN_SIMPLE_MSG has been introduced. This uses some macro magic
which will cause any such calls to generate a warning, but this is
turned off by default to avoid use of the unpleasant macros in normal
circumstances.

This is a large changeset due to the number of calls that have been
replaced. The only files that contain changes other than simple
substitution of function calls are libbb.h, libbb/herror_msg.c,
libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c,
networking/udhcp/common.h and util-linux/mdev.c additonal macros have
been added for logging so that single parameter and multiple parameter
logging variants exist.

The amount of space saved varies considerably by architecture, and was
found to be as follows (for 'defconfig' using GCC 7.4):

Arm:     -92 bytes
MIPS:    -52 bytes
PPC:   -1836 bytes
x86_64: -938 bytes

Note that for the MIPS architecture only an exception had to be made
disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h)
because it made these files larger on MIPS.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

5 files changed, 6 insertions, 6 deletions

diff --git a/procps/kill.c b/procps/kill.c
index a30a79dd8..4a2eab613 100644
--- a/procps/kill.c
+++ b/procps/kill.c
@@ -268,7 +268,7 @@ int kill_main(int argc UNUSED_PARAM, char **argv)
 #if ENABLE_KILL || ENABLE_KILLALL
 	/* Pid or name is required for kill/killall */
 	if (!arg) {
-		bb_error_msg("you need to specify whom to kill");
+		bb_simple_error_msg("you need to specify whom to kill");
 		return EXIT_FAILURE;
 	}
 
diff --git a/procps/mpstat.c b/procps/mpstat.c
index 4ea1b5d97..52a436a55 100644
--- a/procps/mpstat.c
+++ b/procps/mpstat.c
@@ -931,7 +931,7 @@ int mpstat_main(int argc UNUSED_PARAM, char **argv)
 				/* Get CPU number */
 				unsigned n = xatoi_positive(t);
 				if (n >= G.cpu_nr)
-					bb_error_msg_and_die("not that many processors");
+					bb_simple_error_msg_and_die("not that many processors");
 				n++;
 				G.cpu_bitmap[n >> 3] |= 1 << (n & 7);
 			}
diff --git a/procps/powertop.c b/procps/powertop.c
index e70f5433b..d508b5f78 100644
--- a/procps/powertop.c
+++ b/procps/powertop.c
@@ -657,7 +657,7 @@ static void show_timerstats(void)
 		}
 	} else {
 		bb_putchar('\n');
-		bb_error_msg("no stats available; run as root or"
+		bb_simple_error_msg("no stats available; run as root or"
 				" enable the timer_stats module");
 	}
 }
@@ -707,7 +707,7 @@ int powertop_main(int argc UNUSED_PARAM, char UNUSED_PARAM **argv)
 
 	/* Print warning when we don't have superuser privileges */
 	if (geteuid() != 0)
-		bb_error_msg("run as root to collect enough information");
+		bb_simple_error_msg("run as root to collect enough information");
 
 	/* Get number of CPUs */
 	G.total_cpus = get_cpu_count();
diff --git a/procps/pstree.c b/procps/pstree.c
index 1d124d2d2..67b711168 100644
--- a/procps/pstree.c
+++ b/procps/pstree.c
@@ -404,7 +404,7 @@ int pstree_main(int argc UNUSED_PARAM, char **argv)
 	else {
 		dump_by_user(find_proc(1), uid);
 		if (!G.dumped) {
-			bb_error_msg_and_die("no processes found");
+			bb_simple_error_msg_and_die("no processes found");
 		}
 	}
 
diff --git a/procps/top.c b/procps/top.c
index 89f9d23f4..8fe53324f 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -1229,7 +1229,7 @@ int top_main(int argc UNUSED_PARAM, char **argv)
 #endif
 		} /* end of "while we read /proc" */
 		if (ntop == 0) {
-			bb_error_msg("no process info in /proc");
+			bb_simple_error_msg("no process info in /proc");
 			break;
 		}