Re: [PATCH] lib: replace libprocps/libproc2 with /proc-based process enumeration

["Bai, Zongyao" <zongyao.bai@intel.com>]

Hi Jia,

LGTM

  Reviewed-by: Zongyao Bai <zongyao.bai@intel.com>


On 6/3/2026 11:28 AM, Jia Yao wrote:
> The previous code used compile-time #ifdef HAVE_LIBPROCPS / HAVE_LIBPROC2
> to select between two incompatible APIs, requiring separate builds for
> Ubuntu 22.04 (libprocps) and Ubuntu 24.04 (libproc2).
> Replace the platform-specific code with internal static helpers in
> igt_aux.c that read /proc/<pid>/status directly, requiring no external
> library and working identically across distro versions.
> The libprocps/libproc2 meson dependencies have been removed entirely.
>
> Cc: Zongyao Bai <zongyao.bai@intel.com>
> Signed-off-by: Jia Yao <jia.yao@intel.com>
> ---
>   lib/igt_aux.c   | 203 +++++++++++++++++++++++++++++++-----------------
>   lib/meson.build |   6 --
>   meson.build     |  13 +---
>   3 files changed, 131 insertions(+), 91 deletions(-)
>
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index 87c0593a4..0d250ae2f 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -53,12 +53,6 @@
>   #include <assert.h>
>   #include <grp.h>
>   
> -#ifdef HAVE_LIBPROCPS
> -#  include <proc/readproc.h>
> -#elif HAVE_LIBPROC2
> -#  include <libproc2/pids.h>
> -#endif
> -
>   #include <dirent.h>
>   #ifdef __linux__
>   #  include <libudev.h>
> @@ -1285,93 +1279,156 @@ void igt_unlock_mem(void)
>   	locked_mem = NULL;
>   }
>   
> +/*
> + * Internal /proc-based process iterator.  Reads /proc/<pid>/status directly
> + * so there is no dependency on libprocps or libproc2.
> + *
> + * /proc/<pid>/status fields used:
> + *   Name:  <comm>  - command name (kernel escapes spaces, so %s is safe)
> + *   Pid:   <pid>
> + *   Uid:   ruid euid suid fsuid
> + *   Gid:   rgid egid sgid fsgid
> + */
> +struct procps_iter {
> +	DIR   *procdir;
> +	char   comm[64];
> +	pid_t  tid;
> +	uid_t  euid;
> +	gid_t  egid;
> +};
> +
> +static struct procps_iter *procps_open(void)
> +{
> +	struct procps_iter *iter = calloc(1, sizeof(*iter));
> +
> +	if (!iter)
> +		return NULL;
> +
> +	iter->procdir = opendir("/proc");
> +	if (!iter->procdir) {
> +		free(iter);
> +		return NULL;
> +	}
> +
> +	return iter;
> +}
> +
> +static bool procps_next(struct procps_iter *iter,
> +			pid_t *tid, uid_t *euid, gid_t *egid,
> +			const char **comm)
> +{
> +	struct dirent *ent;
> +
> +	if (!iter || !iter->procdir)
> +		return false;
> +
> +	while ((ent = readdir(iter->procdir))) {
> +		char path[64];
> +		FILE *f;
> +		pid_t _tid = 0;
> +		uid_t _euid = 0;
> +		gid_t _egid = 0;
> +		char _comm[64] = "";
> +		int fields = 0;   /* bit 0=Name, 1=Pid, 2=Uid, 3=Gid */
> +		char line[256];
> +
> +		if (ent->d_name[0] < '1' || ent->d_name[0] > '9')
> +			continue;
> +
> +		snprintf(path, sizeof(path), "/proc/%.20s/status", ent->d_name);
> +
> +		f = fopen(path, "r");
> +		if (!f)
> +			continue;
> +
> +		while (fields != 0xf && fgets(line, sizeof(line), f)) {
> +			if (!(fields & 0x1) && strncmp(line, "Name:", 5) == 0) {
> +				if (sscanf(line + 5, " %63s", _comm) == 1)
> +					fields |= 0x1;
> +			} else if (!(fields & 0x2) && strncmp(line, "Pid:", 4) == 0) {
> +				if (sscanf(line + 4, " %d", &_tid) == 1)
> +					fields |= 0x2;
> +			} else if (!(fields & 0x4) && strncmp(line, "Uid:", 4) == 0) {
> +				/* skip ruid, read euid */
> +				unsigned int _e;
> +
> +				if (sscanf(line + 4, " %*u %u", &_e) == 1) {
> +					_euid = (uid_t)_e;
> +					fields |= 0x4;
> +				}
> +			} else if (!(fields & 0x8) && strncmp(line, "Gid:", 4) == 0) {
> +				/* skip rgid, read egid */
> +				unsigned int _e;
> +
> +				if (sscanf(line + 4, " %*u %u", &_e) == 1) {
> +					_egid = (gid_t)_e;
> +					fields |= 0x8;
> +				}
> +			}
> +		}
> +
> +		fclose(f);
> +
> +		if (_tid <= 0)
> +			continue;
> +
> +		iter->tid  = _tid;
> +		iter->euid = _euid;
> +		iter->egid = _egid;
> +		snprintf(iter->comm, sizeof(iter->comm), "%s", _comm);
> +
> +		*tid  = iter->tid;
> +		*euid = iter->euid;
> +		*egid = iter->egid;
> +		*comm = iter->comm;
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static void procps_close(struct procps_iter *iter)
> +{
> +	if (!iter)
> +		return;
> +
> +	if (iter->procdir)
> +		closedir(iter->procdir);
> +
> +	free(iter);
> +}
> +
>   struct igt_process {
> -#ifdef HAVE_LIBPROCPS
> -	PROCTAB * proc;
> -	proc_t *proc_info;
> -#elif HAVE_LIBPROC2
> -	struct pids_info *info;
> -	struct pids_stack *stack;
> -#endif
> +	struct procps_iter *iter;
>   	pid_t tid;
> -	pid_t euid;
> -	pid_t egid;
> -	char *comm;
> +	uid_t euid;
> +	gid_t egid;
> +	const char *comm;
>   };
>   
>   static void open_process(struct igt_process *prcs)
>   {
> -#ifdef HAVE_LIBPROCPS
> -	prcs->proc = openproc(PROC_FILLCOM | PROC_FILLSTAT | PROC_FILLARG);
> -	igt_assert_f(prcs->proc != NULL, "procps open failed\n");
> -	prcs->proc_info = NULL;
> -#elif HAVE_LIBPROC2
> -	enum pids_item Items[] = { PIDS_ID_PID, PIDS_ID_EUID, PIDS_ID_EGID, PIDS_CMD };
> -	int err;
> -
> -	prcs->info = NULL;
> -	err = procps_pids_new(&prcs->info, Items, 4);
> -	igt_assert_f(err >= 0, "procps-ng open failed\n");
> -	prcs->stack = NULL;
> -#endif
> +	prcs->iter = procps_open();
> +	igt_assert_f(prcs->iter, "procps open failed (no /proc filesystem?)\n");
>   	prcs->tid = 0;
>   	prcs->comm = NULL;
>   }
>   
>   static void close_process(struct igt_process *prcs)
>   {
> -#ifdef HAVE_LIBPROCPS
> -	if (prcs->proc_info)
> -		freeproc(prcs->proc_info);
> -
> -	closeproc(prcs->proc);
> -	prcs->proc_info = NULL;
> -	prcs->proc = NULL;
> -#elif HAVE_LIBPROC2
> -	procps_pids_unref(&prcs->info);
> -	prcs->info = NULL;
> -#endif
> +	procps_close(prcs->iter);
> +	prcs->iter = NULL;
>   	prcs->tid = 0;
>   	prcs->comm = NULL;
>   }
>   
>   static bool get_process_ids(struct igt_process *prcs)
>   {
> -#ifdef HAVE_LIBPROCPS
> -	if (prcs->proc_info)
> -		freeproc(prcs->proc_info);
> -
> -	prcs->tid = 0;
> -	prcs->comm = NULL;
> -	prcs->proc_info = readproc(prcs->proc, NULL);
> -
> -	if (prcs->proc_info) {
> -		prcs->tid = prcs->proc_info->tid;
> -		prcs->euid = prcs->proc_info->euid;
> -		prcs->egid = prcs->proc_info->egid;
> -		prcs->comm = prcs->proc_info->cmd;
> -	}
> -#elif HAVE_LIBPROC2
> -	enum rel_items { EU_PID, EU_EUID, EU_EGID, EU_CMD }; // order at open
> -
>   	prcs->tid = 0;
>   	prcs->comm = NULL;
> -	prcs->stack = procps_pids_get(prcs->info, PIDS_FETCH_TASKS_ONLY);
> -	if (prcs->stack) {
> -#if defined(HAVE_LIBPROC2_POST_4_0_5_API)
> -		prcs->tid = PIDS_VAL(EU_PID, s_int, prcs->stack);
> -		prcs->euid = PIDS_VAL(EU_EUID, s_int, prcs->stack);
> -		prcs->egid = PIDS_VAL(EU_EGID, s_int, prcs->stack);
> -		prcs->comm = PIDS_VAL(EU_CMD, str, prcs->stack);
> -#else
> -		prcs->tid = PIDS_VAL(EU_PID, s_int, prcs->stack, prcs->info);
> -		prcs->euid = PIDS_VAL(EU_EUID, s_int, prcs->stack, prcs->info);
> -		prcs->egid = PIDS_VAL(EU_EGID, s_int, prcs->stack, prcs->info);
> -		prcs->comm = PIDS_VAL(EU_CMD, str, prcs->stack, prcs->info);
> -#endif
> -	}
> -#endif
> -	return prcs->tid != 0;
> +	return procps_next(prcs->iter,
> +			   &prcs->tid, &prcs->euid, &prcs->egid,
> +			   &prcs->comm);
>   }
>   
>   /**
> diff --git a/lib/meson.build b/lib/meson.build
> index a8d6566ae..f25ecd8b2 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -257,12 +257,6 @@ if build_xe_eudebug
>   	lib_sources += 'xe/xe_eudebug.c'
>   endif
>   
> -if libprocps.found()
> -	lib_deps += libprocps
> -else
> -	lib_deps += libproc2
> -endif
> -
>   if get_option('srcdir') != ''
>       srcdir = join_paths(get_option('srcdir'), 'tests')
>   else
> diff --git a/meson.build b/meson.build
> index e750f7a51..4def24cbc 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -133,18 +133,7 @@ build_info += 'With libdrm: ' + ','.join(libdrm_info)
>   
>   pciaccess = dependency('pciaccess', version : '>=0.10')
>   libkmod = dependency('libkmod')
> -libprocps = dependency('libprocps', required : false)
> -libproc2 = dependency('libproc2', required : false)
> -if libprocps.found()
> -  config.set('HAVE_LIBPROCPS', 1)
> -elif libproc2.found()
> -  config.set('HAVE_LIBPROC2', 1)
> -  if libproc2.version().version_compare('>= 4.0.5')
> -    config.set('HAVE_LIBPROC2_POST_4_0_5_API', 1)
> -  endif
> -else
> -  error('Either libprocps or libproc2 is required')
> -endif
> +# igt_procps.c reads /proc directly; libprocps and libproc2 are not needed.
>   
>   libunwind = dependency('libunwind', required : get_option('libunwind'))
>   if libunwind.found()