Re: [PATCH v2 5/6] treewide: Replace perror() calls with calls to logging functions

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 18, 2024 at 09:14:26AM +0200, Stefano Brivio wrote:
> perror() prints directly to standard error, but in many cases standard
> error might be already closed, or we might want to skip logging, based
> on configuration. Our logging functions provide all that.
> 
> While at it, make errors more descriptive, replacing some of the
> existing basic perror-style messages.
> 
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

As noted elsewhere, I'm not a huge fan of the _perror() helpers, but
regardless of that this is a big improvement to clarity.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  arch.c      | 10 +++++-----
>  conf.c      |  6 ++----
>  isolation.c | 18 ++++++++----------
>  log.c       | 12 ++++--------
>  passt.c     | 41 ++++++++++++++++-------------------------
>  pasta.c     |  9 +++------
>  6 files changed, 38 insertions(+), 58 deletions(-)
> 
> diff --git a/arch.c b/arch.c
> index 80a41bc..04bebfc 100644
> --- a/arch.c
> +++ b/arch.c
> @@ -18,6 +18,8 @@
>  #include <string.h>
>  #include <unistd.h>
>  
> +#include "log.h"
> +
>  /**
>   * arch_avx2_exec() - Switch to AVX2 build if supported
>   * @argv:	Arguments from command line
> @@ -28,10 +30,8 @@ void arch_avx2_exec(char **argv)
>  	char exe[PATH_MAX] = { 0 };
>  	const char *p;
>  
> -	if (readlink("/proc/self/exe", exe, PATH_MAX - 1) < 0) {
> -		perror("readlink /proc/self/exe");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (readlink("/proc/self/exe", exe, PATH_MAX - 1) < 0)
> +		die_perror("Failed to read own /proc/self/exe link");
>  
>  	p = strstr(exe, ".avx2");
>  	if (p && strlen(p) == strlen(".avx2"))
> @@ -42,7 +42,7 @@ void arch_avx2_exec(char **argv)
>  
>  		snprintf(new_path, PATH_MAX + sizeof(".avx2"), "%s.avx2", exe);
>  		execve(new_path, argv, environ);
> -		perror("Can't run AVX2 build, using non-AVX2 version");
> +		warn_perror("Can't run AVX2 build, using non-AVX2 version");
>  	}
>  }
>  #else
> diff --git a/conf.c b/conf.c
> index 14feee1..344eb07 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -1098,10 +1098,8 @@ static void conf_ugid(char *runas, uid_t *uid, gid_t *gid)
>  		const struct passwd *pw;
>  		/* cppcheck-suppress getpwnamCalled */
>  		pw = getpwnam("nobody");
> -		if (!pw) {
> -			perror("getpwnam");
> -			exit(EXIT_FAILURE);
> -		}
> +		if (!pw)
> +			die_perror("Can't get password file entry for nobody");
>  
>  		*uid = pw->pw_uid;
>  		*gid = pw->pw_gid;
> diff --git a/isolation.c b/isolation.c
> index ca2c68b..c936674 100644
> --- a/isolation.c
> +++ b/isolation.c
> @@ -316,34 +316,34 @@ int isolate_prefork(const struct ctx *c)
>  		flags |= CLONE_NEWPID;
>  
>  	if (unshare(flags)) {
> -		perror("unshare");
> +		err_perror("Failed to detach isolating namespaces");
>  		return -errno;
>  	}
>  
>  	if (mount("", "/", "", MS_UNBINDABLE | MS_REC, NULL)) {
> -		perror("mount /");
> +		err_perror("Failed to remount /");
>  		return -errno;
>  	}
>  
>  	if (mount("", TMPDIR, "tmpfs",
>  		  MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RDONLY,
>  		  "nr_inodes=2,nr_blocks=0")) {
> -		perror("mount tmpfs");
> +		err_perror("Failed to mount empty tmpfs for pivot_root()");
>  		return -errno;
>  	}
>  
>  	if (chdir(TMPDIR)) {
> -		perror("chdir");
> +		err_perror("Failed to change directory into empty tmpfs");
>  		return -errno;
>  	}
>  
>  	if (syscall(SYS_pivot_root, ".", ".")) {
> -		perror("pivot_root");
> +		err_perror("Failed to pivot_root() into empty tmpfs");
>  		return -errno;
>  	}
>  
>  	if (umount2(".", MNT_DETACH | UMOUNT_NOFOLLOW)) {
> -		perror("umount2");
> +		err_perror("Failed to unmount original root filesystem");
>  		return -errno;
>  	}
>  
> @@ -388,8 +388,6 @@ void isolate_postfork(const struct ctx *c)
>  	}
>  
>  	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
> -	    prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog)) {
> -		perror("prctl");
> -		exit(EXIT_FAILURE);
> -	}
> +	    prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog))
> +		die_perror("Failed to apply seccomp filter");
>  }
> diff --git a/log.c b/log.c
> index 9ddc58c..ec833c4 100644
> --- a/log.c
> +++ b/log.c
> @@ -208,10 +208,8 @@ void logfile_init(const char *name, const char *path, size_t size)
>  	char nl = '\n', exe[PATH_MAX] = { 0 };
>  	int n;
>  
> -	if (readlink("/proc/self/exe", exe, PATH_MAX - 1) < 0) {
> -		perror("readlink /proc/self/exe");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (readlink("/proc/self/exe", exe, PATH_MAX - 1) < 0)
> +		die_perror("Failed to read own /proc/self/exe link");
>  
>  	log_file = open(path, O_CREAT | O_TRUNC | O_APPEND | O_RDWR | O_CLOEXEC,
>  			S_IRUSR | S_IWUSR);
> @@ -224,10 +222,8 @@ void logfile_init(const char *name, const char *path, size_t size)
>  		     name, exe, getpid());
>  
>  	if (write(log_file, log_header, n) <= 0 ||
> -	    write(log_file, &nl, 1) <= 0) {
> -		perror("Couldn't write to log file\n");
> -		exit(EXIT_FAILURE);
> -	}
> +	    write(log_file, &nl, 1) <= 0)
> +		die_perror("Couldn't write to log file");
>  
>  	/* For FALLOC_FL_COLLAPSE_RANGE: VFS block size can be up to one page */
>  	log_cut_size = ROUND_UP(log_size * LOGFILE_CUT_RATIO / 100, PAGE_SIZE);
> diff --git a/passt.c b/passt.c
> index 7436120..542d3fb 100644
> --- a/passt.c
> +++ b/passt.c
> @@ -136,14 +136,13 @@ static void secret_init(struct ctx *c)
>  	}
>  	if (dev_random >= 0)
>  		close(dev_random);
> -	if (random_read < sizeof(c->hash_secret)) {
> +
> +	if (random_read < sizeof(c->hash_secret))
>  #else
>  	if (getrandom(&c->hash_secret, sizeof(c->hash_secret),
> -		      GRND_RANDOM) < 0) {
> +		      GRND_RANDOM) < 0)
>  #endif /* !HAS_GETRANDOM */
> -		perror("TCP initial sequence getrandom");
> -		exit(EXIT_FAILURE);
> -	}
> +		die_perror("Failed to get random bytes for hash table and TCP");
>  }
>  
>  /**
> @@ -250,20 +249,16 @@ int main(int argc, char **argv)
>  	madvise(pkt_buf, TAP_BUF_BYTES, MADV_HUGEPAGE);
>  
>  	c.epollfd = epoll_create1(EPOLL_CLOEXEC);
> -	if (c.epollfd == -1) {
> -		perror("epoll_create1");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (c.epollfd == -1)
> +		die_perror("Failed to create epoll file descriptor");
> +
> +	if (getrlimit(RLIMIT_NOFILE, &limit))
> +		die_perror("Failed to get maximum value of open files limit");
>  
> -	if (getrlimit(RLIMIT_NOFILE, &limit)) {
> -		perror("getrlimit");
> -		exit(EXIT_FAILURE);
> -	}
>  	c.nofile = limit.rlim_cur = limit.rlim_max;
> -	if (setrlimit(RLIMIT_NOFILE, &limit)) {
> -		perror("setrlimit");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (setrlimit(RLIMIT_NOFILE, &limit))
> +		die_perror("Failed to set current limit for open files");
> +
>  	sock_probe_mem(&c);
>  
>  	conf(&c, argc, argv);
> @@ -293,10 +288,8 @@ int main(int argc, char **argv)
>  	pcap_init(&c);
>  
>  	if (!c.foreground) {
> -		if ((devnull_fd = open("/dev/null", O_RDWR | O_CLOEXEC)) < 0) {
> -			perror("/dev/null open");
> -			exit(EXIT_FAILURE);
> -		}
> +		if ((devnull_fd = open("/dev/null", O_RDWR | O_CLOEXEC)) < 0)
> +			die_perror("Failed to open /dev/null");
>  	}
>  
>  	if (isolate_prefork(&c))
> @@ -324,10 +317,8 @@ loop:
>  	/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
>  	/* cppcheck-suppress [duplicateValueTernary, unmatchedSuppression] */
>  	nfds = epoll_wait(c.epollfd, events, EPOLL_EVENTS, TIMER_INTERVAL);
> -	if (nfds == -1 && errno != EINTR) {
> -		perror("epoll_wait");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (nfds == -1 && errno != EINTR)
> +		die_perror("epoll_wait() failed in main loop");
>  
>  	clock_gettime(CLOCK_MONOTONIC, &now);
>  
> diff --git a/pasta.c b/pasta.c
> index b85ea2b..d08391f 100644
> --- a/pasta.c
> +++ b/pasta.c
> @@ -197,8 +197,7 @@ static int pasta_spawn_cmd(void *arg)
>  	a = (const struct pasta_spawn_cmd_arg *)arg;
>  	execvp(a->exe, a->argv);
>  
> -	perror("execvp");
> -	exit(EXIT_FAILURE);
> +	die_perror("Failed to start command or shell");
>  }
>  
>  /**
> @@ -261,10 +260,8 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
>  				   CLONE_NEWUTS | CLONE_NEWNS  | SIGCHLD,
>  				   (void *)&arg);
>  
> -	if (pasta_child_pid == -1) {
> -		perror("clone");
> -		exit(EXIT_FAILURE);
> -	}
> +	if (pasta_child_pid == -1)
> +		die_perror("Failed to clone process with detached namespaces");
>  
>  	NS_CALL(pasta_wait_for_ns, c);
>  	if (c->pasta_netns_fd < 0)

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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