[pacman-dev] [PATCH] Check mountpoint read-only status when checking space

[Dan McGee]

This is a bit of a stopgap solution for the problem, but an easier one than
revamping the file conflict checking code to support the same stuff. Using
some more gross autoconf magic, figure out which struct field we need to
look at to determine read-only status and store that on our mountpoint
struct. If we find out we needed this partition after calculating size
requirements, then toss an error.

Signed-off-by: Dan McGee <dan at archlinux.org>
---
Note: there are two definite areas for improvement here- we would fail on a
package uninstall due to us not setting the ->used flag there. We may want two
flags for this purpose- used, and "getting installed to" or something. Second
is we don't do anything with directories and symlinks, so this would still fail
if /boot was read-only:

/var/lib/myfile
/boot/youlose
/boot/youloseagain -> /var/lib/myfile

-Dan

 configure.ac            |    4 ++++
 lib/libalpm/diskspace.c |   30 +++++++++++++++++++++++-------
 lib/libalpm/diskspace.h |    1 +
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 47d6093..1039bba 100644
--- a/configure.ac
+++ b/configure.ac
@@ -194,6 +194,10 @@ AC_CHECK_FUNCS([geteuid getmntinfo realpath regcomp strcasecmp \
                 wcwidth uname])
 # For the diskspace code
 FS_STATS_TYPE
+AC_CHECK_MEMBERS([struct statvfs.f_flag],,,[[#include <sys/statvfs.h>]])
+AC_CHECK_MEMBERS([struct statfs.f_flags],,,[[#include <sys/param.h>
+                  #include <sys/mount.h>]])
+
 # Enable large file support if available
 AC_SYS_LARGEFILE
 
diff --git a/lib/libalpm/diskspace.c b/lib/libalpm/diskspace.c
index ae2edf7..d47f9be 100644
--- a/lib/libalpm/diskspace.c
+++ b/lib/libalpm/diskspace.c
@@ -19,6 +19,7 @@
 
 #include "config.h"
 
+#include <errno.h>
 #if defined(HAVE_MNTENT_H)
 #include <mntent.h>
 #endif
@@ -66,7 +67,7 @@ static alpm_list_t *mount_point_list(void)
 #if defined HAVE_GETMNTENT
 	struct mntent *mnt;
 	FILE *fp;
-	FSSTATSTYPE fsp;
+	struct statvfs fsp;
 
 	fp = setmntent(MOUNTED, "r");
 
@@ -75,16 +76,22 @@ static alpm_list_t *mount_point_list(void)
 	}
 
 	while((mnt = getmntent(fp))) {
+		if(!mnt) {
+			_alpm_log(PM_LOG_WARNING, _("could not get filesystem information\n"));
+			continue;
+		}
 		if(statvfs(mnt->mnt_dir, &fsp) != 0) {
 			_alpm_log(PM_LOG_WARNING,
-					_("could not get filesystem information for %s\n"), mnt->mnt_dir);
+					_("could not get filesystem information for %s: %s\n"),
+					mnt->mnt_dir, strerror(errno));
 			continue;
 		}
 
 		MALLOC(mp, sizeof(alpm_mountpoint_t), RET_ERR(PM_ERR_MEMORY, NULL));
 		mp->mount_dir = strdup(mnt->mnt_dir);
-		mp->mount_dir_len = strlen(mnt->mnt_dir);
-		memcpy(&(mp->fsp), &fsp, sizeof(FSSTATSTYPE));
+		mp->mount_dir_len = strlen(mp->mount_dir);
+		memcpy(&(mp->fsp), &fsp, sizeof(struct statvfs));
+		mp->read_only = fsp.f_flag & ST_RDONLY;
 
 		mp->blocks_needed = 0l;
 		mp->max_blocks_needed = 0l;
@@ -101,14 +108,19 @@ static alpm_list_t *mount_point_list(void)
 	entries = getmntinfo(&fsp, MNT_NOWAIT);
 
 	if (entries < 0) {
-		return NULL;
+		return(NULL);
 	}
 
 	for(; entries-- > 0; fsp++) {
 		MALLOC(mp, sizeof(alpm_mountpoint_t), RET_ERR(PM_ERR_MEMORY, NULL));
 		mp->mount_dir = strdup(fsp->f_mntonname);
-		mp->mount_dir_len = strlen(mnt->mnt_dir);
+		mp->mount_dir_len = strlen(mp->mount_dir);
 		memcpy(&(mp->fsp), fsp, sizeof(FSSTATSTYPE));
+#if defined HAVE_STRUCT_STATVFS_F_FLAG
+		mp->read_only = fsp.f_flag & ST_RDONLY;
+#elif defined HAVE_STRUCT_STATFS_F_FLAGS
+		mp->read_only = fsp.f_flags & MNT_RDONLY;
+#endif
 
 		mp->blocks_needed = 0l;
 		mp->max_blocks_needed = 0l;
@@ -303,7 +315,11 @@ int _alpm_check_diskspace(pmtrans_t *trans, pmdb_t *db_local)
 
 	for(i = mount_points; i; i = alpm_list_next(i)) {
 		alpm_mountpoint_t *data = i->data;
-		if(data->used == 1) {
+		if(data->used && data->read_only) {
+			_alpm_log(PM_LOG_ERROR, _("Partition %s is mounted read only\n"),
+					data->mount_dir);
+			abort = 1;
+		} else if(data->used) {
 			/* cushion is roughly min(5% capacity, 20MiB) */
 			long fivepc = ((long)data->fsp.f_blocks / 20) + 1;
 			long twentymb = (20 * 1024 * 1024 / (long)data->fsp.f_bsize) + 1;
diff --git a/lib/libalpm/diskspace.h b/lib/libalpm/diskspace.h
index ae99d0c..7c7dceb 100644
--- a/lib/libalpm/diskspace.h
+++ b/lib/libalpm/diskspace.h
@@ -37,6 +37,7 @@ typedef struct __alpm_mountpoint_t {
 	long blocks_needed;
 	long max_blocks_needed;
 	int used;
+	int read_only;
 	FSSTATSTYPE fsp;
 } alpm_mountpoint_t;
 
-- 
1.7.4