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sparsebundle: Handle locking properly

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This commit is contained in:
Dave Vasilevsky 2013-03-11 16:50:12 -04:00
parent 9953374b25
commit cdb0338883
1 changed files with 21 additions and 11 deletions
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32
BasiliskII/src/Unix/disk_sparsebundle.cpp
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@ -24,7 +24,11 @@
#include <errno.h>
#include <limits.h>
#include <algorithm>
#if defined __APPLE__ && defined __MACH__
#define __MACOSX__ 1
#endif
struct disk_sparsebundle : disk_generic {
disk_sparsebundle(const char *bands, int fd, bool read_only,
loff_t band_size, loff_t total_size)
@ -232,19 +236,19 @@ protected:
};
static int try_open(const char *path, bool read_only) {
static int try_open(const char *path, bool read_only, bool *locked) {
int oflags = (read_only ? O_RDONLY : O_RDWR);
int lockflags = 0;
#if defined(__MACOSX__)
oflags |= O_EXLOCK;
lockflags = O_NONBLOCK | (read_only ? O_SHLOCK : O_EXLOCK);
#endif
int fd = open(path, oflags);
int fd = open(path, oflags | lockflags);
#if defined(__MACOSX__)
if (fd == -1) {
if (errno == EOPNOTSUPP) { // no locking support
oflags &= ~O_EXLOCK;
if (errno == EOPNOTSUPP) { // no locking support, try again
fd = open(path, oflags);
} else if (errno == EAGAIN) { // already locked
fprintf(stderr, "sparsebundle: Refusing to double-mount\n");
} else if (errno == EAGAIN) { // locked
*locked = true;
}
}
#endif
@ -284,13 +288,19 @@ disk_generic *disk_sparsebundle_factory(const char *path, bool read_only) {
// Check if we can open it
if (snprintf(buf, PATH_MAX, "%s/%s", path, "token") >= PATH_MAX)
return NULL;
int token = try_open(buf, read_only);
bool locked = false;
int token = try_open(buf, read_only, &locked);
if (token == -1 && !read_only) { // try again, read-only
token = try_open(buf, true, &locked);
if (token != -1 && !read_only)
fprintf(stderr, "sparsebundle: Can only mount read-only\n");
read_only = true;
token = try_open(buf, read_only);
}
if (token == -1) {
fprintf(stderr, "sparsebundle: Can't open the bundle\n");
if (locked)
fprintf(stderr, "sparsebundle: Refusing to double-mount\n");
else
perror("sparsebundle: open failed:");
return NULL;
}