commit edbcc223ea9ef9c3f039352f787af0644d816ee7
Author:     Michael Forney <mfor...@mforney.org>
AuthorDate: Sun Dec 22 13:53:46 2019 -0800
Commit:     Michael Forney <mfor...@mforney.org>
CommitDate: Thu Mar 5 00:45:53 2020 -0800

    libutil/recurse: Use a single path buffer, and directory fd
    
    This way, we don't use PATH_MAX bytes on the stack per path component,
    and don't have to keep copying the complete path around.

diff --git a/chgrp.c b/chgrp.c
index 04b2dd0..d336c88 100644
--- a/chgrp.c
+++ b/chgrp.c
@@ -14,18 +14,17 @@ static gid_t gid = -1;
 static int   ret = 0;
 
 static void
-chgrp(const char *path, struct stat *st, void *data, struct recursor *r)
+chgrp(int dirfd, const char *name, struct stat *st, void *data, struct 
recursor *r)
 {
        int flags = 0;
 
        if ((r->maxdepth == 0 && r->follow == 'P') || (r->follow == 'H' && 
r->depth) || (hflag && !(r->depth)))
                flags |= AT_SYMLINK_NOFOLLOW;
-
-       if (fchownat(AT_FDCWD, path, -1, gid, flags) < 0) {
-               weprintf("chown %s:", path);
+       if (fchownat(dirfd, name, -1, gid, flags) < 0) {
+               weprintf("chown %s:", r->path);
                ret = 1;
        } else if (S_ISDIR(st->st_mode)) {
-               recurse(path, NULL, r);
+               recurse(dirfd, name, NULL, r);
        }
 }
 
@@ -71,7 +70,7 @@ main(int argc, char *argv[])
        }
 
        for (argc--, argv++; *argv; argc--, argv++)
-               recurse(*argv, NULL, &r);
+               recurse(AT_FDCWD, *argv, NULL, &r);
 
        return ret || recurse_status;
 }
diff --git a/chmod.c b/chmod.c
index 7b9afe8..554959f 100644
--- a/chmod.c
+++ b/chmod.c
@@ -1,4 +1,5 @@
 /* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
 #include <sys/stat.h>
 
 #include "fs.h"
@@ -9,16 +10,16 @@ static mode_t mask    = 0;
 static int    ret     = 0;
 
 static void
-chmodr(const char *path, struct stat *st, void *data, struct recursor *r)
+chmodr(int dirfd, const char *name, struct stat *st, void *data, struct 
recursor *r)
 {
        mode_t m;
 
        m = parsemode(modestr, st->st_mode, mask);
-       if (!S_ISLNK(st->st_mode) && chmod(path, m) < 0) {
-               weprintf("chmod %s:", path);
+       if (!S_ISLNK(st->st_mode) && fchmodat(dirfd, name, m, 0) < 0) {
+               weprintf("chmod %s:", r->path);
                ret = 1;
        } else if (S_ISDIR(st->st_mode)) {
-               recurse(path, NULL, r);
+               recurse(dirfd, name, NULL, r);
        }
 }
 
@@ -71,7 +72,7 @@ done:
                usage();
 
        for (--argc, ++argv; *argv; argc--, argv++)
-               recurse(*argv, NULL, &r);
+               recurse(AT_FDCWD, *argv, NULL, &r);
 
        return ret || recurse_status;
 }
diff --git a/chown.c b/chown.c
index dcd4914..3aaedef 100644
--- a/chown.c
+++ b/chown.c
@@ -17,18 +17,18 @@ static gid_t gid = -1;
 static int   ret = 0;
 
 static void
-chownpwgr(const char *path, struct stat *st, void *data, struct recursor *r)
+chownpwgr(int dirfd, const char *name, struct stat *st, void *data, struct 
recursor *r)
 {
        int flags = 0;
 
        if ((r->maxdepth == 0 && r->follow == 'P') || (r->follow == 'H' && 
r->depth) || (hflag && !(r->depth)))
                flags |= AT_SYMLINK_NOFOLLOW;
 
-       if (fchownat(AT_FDCWD, path, uid, gid, flags) < 0) {
-               weprintf("chown %s:", path);
+       if (fchownat(dirfd, name, uid, gid, flags) < 0) {
+               weprintf("chown %s:", r->path);
                ret = 1;
        } else if (S_ISDIR(st->st_mode)) {
-               recurse(path, NULL, r);
+               recurse(dirfd, name, NULL, r);
        }
 }
 
@@ -99,7 +99,7 @@ main(int argc, char *argv[])
                usage();
 
        for (argc--, argv++; *argv; argc--, argv++)
-               recurse(*argv, NULL, &r);
+               recurse(AT_FDCWD, *argv, NULL, &r);
 
        return ret || recurse_status;
 }
diff --git a/du.c b/du.c
index 4ceac66..fa6a8d6 100644
--- a/du.c
+++ b/du.c
@@ -3,6 +3,7 @@
 #include <sys/types.h>
 
 #include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -35,19 +36,19 @@ nblks(blkcnt_t blocks)
 }
 
 static void
-du(const char *path, struct stat *st, void *data, struct recursor *r)
+du(int dirfd, const char *path, struct stat *st, void *data, struct recursor 
*r)
 {
        off_t *total = data, subtotal;
 
        subtotal = nblks(st->st_blocks);
        if (S_ISDIR(st->st_mode))
-               recurse(path, &subtotal, r);
+               recurse(dirfd, path, &subtotal, r);
        *total += subtotal;
 
        if (!r->depth)
-               printpath(*total, path);
+               printpath(*total, r->path);
        else if (!sflag && r->depth <= maxdepth && (S_ISDIR(st->st_mode) || 
aflag))
-               printpath(subtotal, path);
+               printpath(subtotal, r->path);
 }
 
 static void
@@ -104,11 +105,11 @@ main(int argc, char *argv[])
                blksize = 1024;
 
        if (!argc) {
-               recurse(".", &n, &r);
+               recurse(AT_FDCWD, ".", &n, &r);
        } else {
                for (; *argv; argc--, argv++) {
                        n = 0;
-                       recurse(*argv, &n, &r);
+                       recurse(AT_FDCWD, *argv, &n, &r);
                }
        }
 
diff --git a/fs.h b/fs.h
index 15ae5f4..00ecd3b 100644
--- a/fs.h
+++ b/fs.h
@@ -1,4 +1,5 @@
 /* See LICENSE file for copyright and license details. */
+#include <limits.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -9,7 +10,9 @@ struct history {
 };
 
 struct recursor {
-       void (*fn)(const char *, struct stat *st, void *, struct recursor *);
+       void (*fn)(int, const char *, struct stat *, void *, struct recursor *);
+       char path[PATH_MAX];
+       size_t pathlen;
        struct history *hist;
        int depth;
        int maxdepth;
@@ -37,7 +40,7 @@ extern int rm_status;
 
 extern int recurse_status;
 
-void recurse(const char *, void *, struct recursor *);
+void recurse(int, const char *, void *, struct recursor *);
 
 int cp(const char *, const char *, int);
-void rm(const char *, struct stat *st, void *, struct recursor *);
+void rm(int, const char *, struct stat *st, void *, struct recursor *);
diff --git a/libutil/recurse.c b/libutil/recurse.c
index e150fb9..e21d815 100644
--- a/libutil/recurse.c
+++ b/libutil/recurse.c
@@ -16,27 +16,30 @@
 int recurse_status = 0;
 
 void
-recurse(const char *path, void *data, struct recursor *r)
+recurse(int dirfd, const char *name, void *data, struct recursor *r)
 {
        struct dirent *d;
        struct history *new, *h;
        struct stat st, dst;
        DIR *dp;
-       char subpath[PATH_MAX];
-       int flags = 0;
+       int flags = 0, fd;
+       size_t pathlen = r->pathlen;
+
+       if (dirfd == AT_FDCWD)
+               pathlen = estrlcpy(r->path, name, sizeof(r->path));
 
        if (r->follow == 'P' || (r->follow == 'H' && r->depth))
                flags |= AT_SYMLINK_NOFOLLOW;
 
-       if (fstatat(AT_FDCWD, path, &st, flags) < 0) {
+       if (fstatat(dirfd, name, &st, flags) < 0) {
                if (!(r->flags & SILENT)) {
-                       weprintf("stat %s:", path);
+                       weprintf("stat %s:", r->path);
                        recurse_status = 1;
                }
                return;
        }
        if (!S_ISDIR(st.st_mode)) {
-               r->fn(path, &st, data, r);
+               r->fn(dirfd, name, &st, data, r);
                return;
        }
 
@@ -51,35 +54,39 @@ recurse(const char *path, void *data, struct recursor *r)
                        return;
 
        if (!r->depth && (r->flags & DIRFIRST))
-               r->fn(path, &st, data, r);
+               r->fn(dirfd, name, &st, data, r);
 
        if (!r->maxdepth || r->depth + 1 < r->maxdepth) {
-               if (!(dp = opendir(path))) {
+               fd = openat(dirfd, name, O_RDONLY | O_CLOEXEC | O_DIRECTORY);
+               if (fd < 0) {
+                       weprintf("open %s:", r->path);
+                       recurse_status = 1;
+               }
+               if (!(dp = fdopendir(fd))) {
                        if (!(r->flags & SILENT)) {
-                               weprintf("opendir %s:", path);
+                               weprintf("fdopendir:");
                                recurse_status = 1;
                        }
                        return;
                }
+               if (r->path[pathlen - 1] != '/')
+                       pathlen += estrlcpy(r->path + pathlen, "/", 
sizeof(r->path) - pathlen);
+               if (r->follow == 'H')
+                       flags |= AT_SYMLINK_NOFOLLOW;
                while ((d = readdir(dp))) {
-                       if (r->follow == 'H')
-                               flags |= AT_SYMLINK_NOFOLLOW;
                        if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
                                continue;
-                       estrlcpy(subpath, path, sizeof(subpath));
-                       if (path[strlen(path) - 1] != '/')
-                               estrlcat(subpath, "/", sizeof(subpath));
-                       estrlcat(subpath, d->d_name, sizeof(subpath));
-                       if (fstatat(AT_FDCWD, subpath, &dst, flags) < 0) {
+                       r->pathlen = pathlen + estrlcpy(r->path + pathlen, 
d->d_name, sizeof(r->path) - pathlen);
+                       if (fstatat(fd, d->d_name, &dst, flags) < 0) {
                                if (!(r->flags & SILENT)) {
-                                       weprintf("stat %s:", subpath);
+                                       weprintf("stat %s:", r->path);
                                        recurse_status = 1;
                                }
                        } else if ((r->flags & SAMEDEV) && dst.st_dev != 
st.st_dev) {
                                continue;
                        } else {
                                r->depth++;
-                               r->fn(subpath, &dst, data, r);
+                               r->fn(fd, d->d_name, &dst, data, r);
                                r->depth--;
                        }
                }
@@ -88,7 +95,7 @@ recurse(const char *path, void *data, struct recursor *r)
 
        if (!r->depth) {
                if (!(r->flags & DIRFIRST))
-                       r->fn(path, &st, data, r);
+                       r->fn(dirfd, name, &st, data, r);
 
                while (r->hist) {
                        h = r->hist;
diff --git a/libutil/rm.c b/libutil/rm.c
index 11c20fb..8d4be08 100644
--- a/libutil/rm.c
+++ b/libutil/rm.c
@@ -2,6 +2,7 @@
 #include <sys/stat.h>
 
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <unistd.h>
 
@@ -11,20 +12,20 @@
 int rm_status = 0;
 
 void
-rm(const char *path, struct stat *st, void *data, struct recursor *r)
+rm(int dirfd, const char *name, struct stat *st, void *data, struct recursor 
*r)
 {
        if (!r->maxdepth && S_ISDIR(st->st_mode)) {
-               recurse(path, NULL, r);
+               recurse(dirfd, name, NULL, r);
 
-               if (rmdir(path) < 0) {
+               if (unlinkat(dirfd, name, AT_REMOVEDIR) < 0) {
                        if (!(r->flags & SILENT))
-                               weprintf("rmdir %s:", path);
+                               weprintf("rmdir %s:", r->path);
                        if (!((r->flags & SILENT) && errno == ENOENT))
                                rm_status = 1;
                }
-       } else if (unlink(path) < 0) {
+       } else if (unlinkat(dirfd, name, 0) < 0) {
                if (!(r->flags & SILENT))
-                       weprintf("unlink %s:", path);
+                       weprintf("unlink %s:", r->path);
                if (!((r->flags & SILENT) && errno == ENOENT))
                        rm_status = 1;
        }
diff --git a/mv.c b/mv.c
index 2cf98d1..c93f72d 100644
--- a/mv.c
+++ b/mv.c
@@ -2,6 +2,7 @@
 #include <sys/stat.h>
 
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 
 #include "fs.h"
@@ -21,7 +22,7 @@ mv(const char *s1, const char *s2, int depth)
                cp_aflag = cp_rflag = cp_pflag = 1;
                cp_follow = 'P';
                cp(s1, s2, depth);
-               recurse(s1, NULL, &r);
+               recurse(AT_FDCWD, s1, NULL, &r);
                return (mv_status = cp_status || rm_status);
        }
        mv_status = 1;
diff --git a/rm.c b/rm.c
index 42bc022..b776d0f 100644
--- a/rm.c
+++ b/rm.c
@@ -1,4 +1,6 @@
 /* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
+
 #include "fs.h"
 #include "util.h"
 
@@ -34,7 +36,7 @@ main(int argc, char *argv[])
        }
 
        for (; *argv; argc--, argv++)
-               recurse(*argv, NULL, &r);
+               recurse(AT_FDCWD, *argv, NULL, &r);
 
        return rm_status || recurse_status;
 }
diff --git a/tar.c b/tar.c
index f9158c2..603e544 100644
--- a/tar.c
+++ b/tar.c
@@ -368,14 +368,14 @@ print(char *fname, ssize_t l, char b[BLKSIZ])
 }
 
 static void
-c(const char *path, struct stat *st, void *data, struct recursor *r)
+c(int dirfd, const char *name, struct stat *st, void *data, struct recursor *r)
 {
-       archive(path);
+       archive(r->path);
        if (vflag)
-               puts(path);
+               puts(r->path);
 
        if (S_ISDIR(st->st_mode))
-               recurse(path, NULL, r);
+               recurse(dirfd, name, NULL, r);
 }
 
 static void
@@ -578,7 +578,7 @@ main(int argc, char *argv[])
                if (chdir(dir) < 0)
                        eprintf("chdir %s:", dir);
                for (; *argv; argc--, argv++)
-                       recurse(*argv, NULL, &r);
+                       recurse(AT_FDCWD, *argv, NULL, &r);
                break;
        case 't':
        case 'x':

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