source: npl/system/klibc/patches/Fix-minimal-mv-to-work-across-fs @ a39aa4c

From: maximilian attems <max@stro.at>
Date: Mon, 4 Jul 2011 17:51:52 +0200
Subject: [PATCH] [klibc] Fix minimal mv to work across fs
Forwarded: not-needed

This is the use case in initramfs to keep data from /run to /root/run
before calling switch_root().

copy_file() doesn't yet catch EINTR, but that seems less of an issue
in initramfs.

copy_file() and much logic out of copy() is from Ulrich Dangel.
Thank you for the collaboration on this blocker for
http://bugs.debian.org/627808

While we are it require move to have mv at least 2 arguments passed.

Signed-off-by: Ulrich Dangel <uli@spamt.net>
Signed-off-by: maximilian attems <max@stro.at>
[bwh: This is no longer needed by initramfs-tools starting with version 0.121,
 so can be dropped after the stretch release]
---
 usr/utils/mv.c |  234 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 216 insertions(+), 18 deletions(-)

Index: klibc-2.0~rc2/usr/utils/mv.c
===================================================================
--- klibc-2.0~rc2.orig/usr/utils/mv.c   2012-02-11 18:50:21.000000000 +0000
+++ klibc-2.0~rc2/usr/utils/mv.c        2012-02-11 19:04:54.000000000 +0000
@@ -1,3 +1,6 @@
+#include <errno.h>
+#include <dirent.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -7,10 +10,204 @@
 
 #include <linux/limits.h>
 
+#define BUFFER_SIZE 32768
+
+/* copy_file - copy a file, used on different fs mv */
+static int copy_file(const char *src, const char *dest, mode_t mode)
+{
+       char buf[BUFFER_SIZE];
+       int sfd, dfd;
+       ssize_t len;
+
+       sfd = open(src, O_RDONLY);
+       if (sfd < 0)
+               return -1;
+
+       dfd = open(dest, O_WRONLY | O_CREAT, mode);
+       if (dfd < 0) {
+               close(sfd);
+               return -1;
+       }
+
+       while ((len = read(sfd, buf, sizeof(buf))) > 0) {
+               len = write(dfd, buf, len);
+               if (len < 0) {
+                       close(sfd);
+                       close(dfd);
+                       return -1;
+               }
+       }
+
+       close(sfd);
+       close(dfd);
+       return 0;
+}
+
+/* copy - recursively copy directories */
+static int copy(char *src, const char *dest)
+{
+       int len;
+       struct stat sb, sf;
+       char target[PATH_MAX];
+       char *p;
+
+       p = strrchr(src, '/');
+       if (p) {
+               p++;
+               /* trailing slashes case */
+               if (strlen(p) == 0) {
+                       len = strlen(src) - 1;
+                       p = src;
+                       while (0 < len && p[len] == '/')
+                               p[len--] = '\0';
+                       p = strrchr(p, '/');
+                       p++;
+               }
+       } else {
+               p = src;
+       }
+
+       memset(&sb, 0, sizeof(struct stat));
+       /* might not exist yet */
+       if (stat(dest, &sb) == 0) {
+               if (S_ISDIR(sb.st_mode)) {
+                       len = snprintf(target, PATH_MAX, "%s/%s", dest, p);
+                       if (len  >= PATH_MAX)
+                               return -1;
+               } else {
+                       len = snprintf(target, PATH_MAX, "%s/%s", dest, src);
+                       if (len  >= PATH_MAX)
+                               return -1;
+               }
+       } else {
+               len = snprintf(target, PATH_MAX, "%s", dest);
+               if (len  >= PATH_MAX)
+                       return -1;
+       }
+
+       if (rename(src, target) == 0) {
+               return 0;
+       } else {
+               if (errno != EXDEV)
+                       return -1;
+       }
+
+
+       /* cross fs copy */
+       memset(&sf, 0, sizeof(struct stat));
+       if (stat(src, &sf) < 0)
+               return -1;
+       if (!S_ISDIR(sf.st_mode)) {
+               len = copy_file(src, target, sf.st_mode);
+               if (len == 0)
+                       return 0;
+               else
+                       return -1;
+       }
+
+       DIR *dir;
+       struct dirent *d;
+       char path[PATH_MAX];
+
+       if (mkdir(target, sf.st_mode) < 0)
+               return -1;
+
+       dir = opendir(src);
+       if (!dir) {
+               /* EACCES means we can't read it.
+                * Might be empty and removable. */
+               if (errno != EACCES)
+                       return -1;
+       }
+       while ((d = readdir(dir))) {
+
+               /* Skip . and .. */
+               if (d->d_name[0] == '.' && (d->d_name[1] == '\0'
+                   || (d->d_name[1] == '.' && d->d_name[2] == '\0')))
+                       continue;
+
+               /* skip to long path */
+               if (strlen(src) + 1 + strlen(d->d_name) >= PATH_MAX  - 1)
+                       continue;
+
+               snprintf(path, sizeof path, "%s/%s", src, d->d_name);
+               if (len  >= sizeof path)
+                       return -1;
+
+               memset(&sf, 0, sizeof(struct stat));
+               if (stat(path, &sf) < 0) {
+                       closedir(dir);
+                       return -1;
+               }
+
+               /* recursively copy files and directories */
+               if (copy(path, target) < 0)
+                       return -1;
+       }
+       closedir(dir);
+       return 0;
+}
+
+/* nuke - rm a file or directory recursively */
+static int nuke(const char *src)
+{
+       struct stat sb;
+       DIR *dir;
+       struct dirent *d;
+       char path[PATH_MAX];
+       int len;
+
+       memset(&sb, 0, sizeof(struct stat));
+       /* gone, no work */
+       if (stat(src, &sb) < 0)
+               return 0;
+
+       if (!S_ISDIR(sb.st_mode)) {
+               if (unlink(src) == 0)
+                       return 0;
+               else
+                       return 1;
+       }
+
+       dir = opendir(src);
+       if (!dir) {
+               /* EACCES means we can't read it.
+                * Might be empty and removable. */
+               if (errno != EACCES)
+                       return -1;
+       }
+       while ((d = readdir(dir))) {
+
+               /* Skip . and .. */
+               if (d->d_name[0] == '.' && (d->d_name[1] == '\0'
+                   || (d->d_name[1] == '.' && d->d_name[2] == '\0')))
+                       continue;
+
+               /* skip to long path */
+               if (strlen(src) + 1 + strlen(d->d_name) >= PATH_MAX  - 1)
+                       continue;
+
+               len = snprintf(path, sizeof path, "%s/%s", src, d->d_name);
+               if (len  >= sizeof path)
+                       return -1;
+
+               memset(&sb, 0, sizeof(struct stat));
+               if (stat(path, &sb) < 0) {
+                       closedir(dir);
+                       return -1;
+               }
+
+               if (nuke(path) < 0)
+                       return -1;
+       }
+       closedir(dir);
+       rmdir(src);
+       return 0;
+}
+
 int main(int argc, char *argv[])
 {
        int c, f;
-       char *p;
        struct stat sb;
 
        f = 0;
@@ -32,11 +229,13 @@
 
        } while (1);
 
-       if (optind == argc) {
+       /* not enough arguments */
+       if (argc - optind < 2) {
                fprintf(stderr, "Usage: %s [-f] source dest\n", argv[0]);
                return 1;
        }
 
+       /* check on many archs if destination is a directory to mv in */
        memset(&sb, 0, sizeof(struct stat));
        if (stat(argv[argc - 1], &sb) < 0 && argc - optind > 2) {
                if (!(S_ISDIR(sb.st_mode))) {
@@ -47,23 +246,22 @@
                }
        }
 
-       for (c = optind; c < argc - 1; c++) {
-               char target[PATH_MAX];
-
-               p = strrchr(argv[c], '/');
-               p++;
-
-               if (S_ISDIR(sb.st_mode))
-                       snprintf(target, PATH_MAX, "%s/%s", argv[argc - 1], p);
-               else
-                       snprintf(target, PATH_MAX, "%s", argv[argc - 1]);
-
-               if (f)
-                       unlink(target);
-
-               if (rename(argv[c], target) == -1)
-                       perror(target);
-       }
+       /* remove destination */
+       if (f)
+               nuke(argv[argc - 1]);
+
+       /* the mv action */
+       for (c = optind; c < argc - 1; c++)
+               if (copy(argv[c], argv[argc - 1]) < 0) {
+                       perror("Could not copy file");
+                       return -1;
+               }
 
+       /* Only rm after sucessfull rename */
+       for (c = optind; c < argc - 1; c++)
+               if (nuke(argv[c]) < 0) {
+                       perror("Could not rm file");
+                       return -1;
+               }
        return 0;
 }