RE: [PATCH v9 07/18] eal: use C library to parse filesystem table

Konstantin Ananyev
2025-12-30T15:26:08Z

> 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 | 58 ++++++++++---------------------
> 1 file changed, 18 insertions(+), 40 deletions(-)
>
> diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
> index d47a19c56a..7161b1a2fb 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) ?
> @@ -226,56 +217,43 @@ 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 */
> - }
> + uint64_t pagesz = default_size;
> + size_t mountpt_len;
>
> - 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 (pagesz_str)
> + pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
>
> - /* 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 {
> - uint64_t pagesz =
> rte_str_to_size(&pagesz_str[pagesize_opt_len]);
> - if (pagesz != hugepage_sz)
> - continue;
> - }
> + if (pagesz != hugepage_sz)
> + continue;
>
> /*
> * 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 +264,10 @@ 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. */
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>

> 2.51.0
>