[RFC] eal: use C library to parse filesystem table

[RFC] eal: use C library to parse filesystem table

[Stephen Hemminger]

Rather than doing parsing of /proc/mounts with open coded string
handling, use the standard C library routines.
These exist in BSD and Linux.

It also avoids any possible issues with escaped strings etc
which the library handles. See getmntent(3) man page.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/eal/linux/eal_hugepage_info.c | 45 ++++++++++---------------------
 1 file changed, 14 insertions(+), 31 deletions(-)

diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
index d47a19c56a..ecc0374204 100644
--- a/lib/eal/linux/eal_hugepage_info.c
+++ b/lib/eal/linux/eal_hugepage_info.c
@@ -13,6 +13,7 @@
 #include <inttypes.h>
 #include <unistd.h>
 #include <errno.h>
+#include <mntent.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 
@@ -195,23 +196,13 @@ get_default_hp_size(void)
 static int
 get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
 {
-	enum proc_mount_fieldnames {
-		DEVICE = 0,
-		MOUNTPT,
-		FSTYPE,
-		OPTIONS,
-		_FIELDNAME_MAX
-	};
 	static uint64_t default_size = 0;
 	const char proc_mounts[] = "/proc/mounts";
-	const char hugetlbfs_str[] = "hugetlbfs";
-	const size_t htlbfs_str_len = sizeof(hugetlbfs_str) - 1;
 	const char pagesize_opt[] = "pagesize=";
 	const size_t pagesize_opt_len = sizeof(pagesize_opt) - 1;
-	const char split_tok = ' ';
-	char *splitstr[_FIELDNAME_MAX];
 	char found[PATH_MAX] = "";
 	char buf[BUFSIZ];
+	struct mntent entry;
 	const struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 	const size_t hugepage_dir_len = (internal_conf->hugepage_dir != NULL) ?
@@ -226,35 +217,28 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
 		return -1;
 	}
 
-	FILE *fd = fopen(proc_mounts, "r");
-	if (fd == NULL)
+	FILE *mounts = setmntent(proc_mounts, "r");
+	if (mounts == NULL)
 		rte_panic("Cannot open %s\n", proc_mounts);
 
 	if (default_size == 0)
 		default_size = get_default_hp_size();
 
-	while (fgets(buf, sizeof(buf), fd)){
+	while (getmntent_r(mounts, &entry, buf, sizeof(buf))) {
 		const char *pagesz_str;
 		size_t mountpt_len = 0;
 
-		if (rte_strsplit(buf, sizeof(buf), splitstr, _FIELDNAME_MAX,
-				split_tok) != _FIELDNAME_MAX) {
-			EAL_LOG(ERR, "Error parsing %s", proc_mounts);
-			break; /* return NULL */
-		}
-
-		if (strncmp(splitstr[FSTYPE], hugetlbfs_str, htlbfs_str_len) != 0)
+		if (strcmp(entry.mnt_type, "hugetlbfs") != 0)
 			continue;
 
-		pagesz_str = strstr(splitstr[OPTIONS], pagesize_opt);
+		pagesz_str = strstr(entry.mnt_opts, pagesize_opt);
 
 		/* if no explicit page size, the default page size is compared */
 		if (pagesz_str == NULL) {
 			if (hugepage_sz != default_size)
 				continue;
-		}
-		/* there is an explicit page size, so check it */
-		else {
+		} else {
+			/* there is an explicit page size, so check it */
 			uint64_t pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
 			if (pagesz != hugepage_sz)
 				continue;
@@ -264,18 +248,17 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
 		 * If no --huge-dir option has been given, we're done.
 		 */
 		if (internal_conf->hugepage_dir == NULL) {
-			strlcpy(found, splitstr[MOUNTPT], len);
+			strlcpy(found, entry.mnt_dir, len);
 			break;
 		}
 
-		mountpt_len = strlen(splitstr[MOUNTPT]);
+		mountpt_len = strlen(entry.mnt_dir);
 
 		/*
 		 * Ignore any mount that doesn't contain the --huge-dir directory
 		 * or where mount point is not a parent path of --huge-dir
 		 */
-		if (strncmp(internal_conf->hugepage_dir, splitstr[MOUNTPT],
-				mountpt_len) != 0 ||
+		if (strncmp(internal_conf->hugepage_dir, entry.mnt_dir, mountpt_len) != 0 ||
 			(hugepage_dir_len > mountpt_len &&
 				internal_conf->hugepage_dir[mountpt_len] != '/')) {
 			continue;
@@ -286,10 +269,10 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
 		 * (so /mnt/1 is preferred over /mnt for matching /mnt/1/2)).
 		 */
 		if (mountpt_len > strlen(found))
-			strlcpy(found, splitstr[MOUNTPT], len);
+			strlcpy(found, entry.mnt_dir, len);
 	} /* end while fgets */
 
-	fclose(fd);
+	endmntent(mounts);
 
 	if (found[0] != '\0') {
 		/* If needed, return the requested dir, not the mount point. */
-- 
2.51.0

Re: [RFC] eal: use C library to parse filesystem table

[Bruce Richardson]

On Sat, Nov 22, 2025 at 11:49:21AM -0800, Stephen Hemminger wrote:
> Rather than doing parsing of /proc/mounts with open coded string
> handling, use the standard C library routines.
> These exist in BSD and Linux.
> 
> It also avoids any possible issues with escaped strings etc
> which the library handles. See getmntent(3) man page.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
Acked-by: Bruce Richardson <bruce.richardson@intel.com>


>  lib/eal/linux/eal_hugepage_info.c | 45 ++++++++++---------------------
>  1 file changed, 14 insertions(+), 31 deletions(-)
> 

<snip>  

> -		pagesz_str = strstr(splitstr[OPTIONS], pagesize_opt);
> +		pagesz_str = strstr(entry.mnt_opts, pagesize_opt);
>  
>  		/* if no explicit page size, the default page size is compared */
>  		if (pagesz_str == NULL) {
>  			if (hugepage_sz != default_size)
>  				continue;
> -		}
> -		/* there is an explicit page size, so check it */
> -		else {
> +		} else {
> +			/* there is an explicit page size, so check it */
>  			uint64_t pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
>  			if (pagesz != hugepage_sz)
>  				continue;

Since you are already changing this part, this if-else block can be
shortened down to avoid duplicating the continue check:

diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
index ecc0374204..0e54b35ce1 100644
--- a/lib/eal/linux/eal_hugepage_info.c
+++ b/lib/eal/linux/eal_hugepage_info.c
@@ -227,22 +227,16 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
        while (getmntent_r(mounts, &entry, buf, sizeof(buf))) {
                const char *pagesz_str;
                size_t mountpt_len = 0;
+               uint64_t pagesz;
 
                if (strcmp(entry.mnt_type, "hugetlbfs") != 0)
                        continue;
 
                pagesz_str = strstr(entry.mnt_opts, pagesize_opt);
-
-               /* if no explicit page size, the default page size is compared */
-               if (pagesz_str == NULL) {
-                       if (hugepage_sz != default_size)
-                               continue;
-               } else {
-                       /* there is an explicit page size, so check it */
-                       uint64_t pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
-                       if (pagesz != hugepage_sz)
-                               continue;
-               }
+               pagesz = (pagesz_str == NULL) ? default_size :
+                               rte_str_to_size(&pagesz_str[pagesize_opt_len]);
+               if (pagesz != hugepage_sz)
+                       continue;
 
                /*
                 * If no --huge-dir option has been given, we're done.