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filewatch_inotify: handle misaligned inotify_event entries

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This shouldn't be needed, as according to the Linux inotify(7) man page,
the entries are supposed to be aligned. It looks like libinotify-kqueue
doesn't respect this and doesn't properly zero-pad the name field.
This commit is contained in:
Andrei Alexeyev 2022-03-05 21:59:27 +02:00
parent 287c77cc8b
commit c24abd2b92
No known key found for this signature in database
GPG key ID: 72D26128040B9690
1 changed files with 87 additions and 51 deletions
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138
src/filewatch/filewatch_inotify.c
View file

@ -13,6 +13,7 @@
#include "events.h"
#include "vfs/syspath_public.h"
#include <alloca.h>
#include <errno.h>
#include <stdio.h>
#include <sys/inotify.h>
@ -378,66 +379,101 @@ void filewatch_unwatch(FileWatch *fw) {
SDL_UnlockMutex(FW.modify_mtx);
}
static void filewatch_process_events(ssize_t bufsize, char buf[bufsize]) {
struct inotify_event *e;
static uint32_t filewatch_process_event(
struct inotify_event *e
IF_FW_DEBUG(, StringBuffer *sbuf)
) {
WDRecord *rec = wdrecord_get(e->wd, false);
IF_FW_DEBUG(
strbuf_clear(sbuf);
dump_events(sbuf, e->mask);
FW_DEBUG("wd %i :: %s :: %s", e->wd, e->name, sbuf->start);
)
if(!rec) {
return e->len;
}
for(DirWatch *dw = rec->dirwatch_list; dw; dw = dw->next) {
if(dw->wd != e->wd) {
continue;
}
FW_DEBUG("Match dir %s", dw->path);
if(e->mask & IN_ISDIR) {
if(e->mask & (IN_MOVE_SELF | IN_DELETE_SELF | IN_IGNORED)) {
dirwatch_invalidate(dw);
}
continue;
}
for(FileWatch *fw = dw->filewatch_list; fw; fw = fw->next) {
if(strcmp(fw->filename, e->name)) {
FW_DEBUG("* %p %s != %s", fw, fw->filename, e->name);
continue;
}
FW_DEBUG("Match file %s/%s", dw->path, fw->filename);
if(e->mask & (IN_DELETE | IN_MOVED_FROM)) {
fw->deleted = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
} else if(e->mask & (IN_CREATE | IN_MOVED_TO)) {
fw->deleted = false;
fw->updated = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
} else if(e->mask & (IN_CLOSE_WRITE | IN_MODIFY)) {
fw->updated = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
}
}
}
return e->len;
}
static uint32_t filewatch_process_event_misaligned(
size_t bufsize, char buf[bufsize]
IF_FW_DEBUG(, StringBuffer *sbuf)
) {
uint32_t sz;
memcpy(&sz, buf + offsetof(struct inotify_event, len), sizeof(sz));
assert(sz <= bufsize);
struct inotify_event *e = alloca(sizeof(*e) + sz);
memcpy(e, buf, sizeof(*e));
filewatch_process_event(e IF_FW_DEBUG(, sbuf));
return sz;
}
static void filewatch_process_events(ssize_t bufsize, char buf[bufsize]) {
IF_FW_DEBUG(
StringBuffer sbuf = {};
)
for(ssize_t i = 0; i < bufsize;) {
e = CASTPTR_ASSUME_ALIGNED(buf + i, struct inotify_event);
WDRecord *rec = wdrecord_get(e->wd, false);
uintptr_t misalign = ((uintptr_t)(buf + i) & (alignof(struct inotify_event) - 1));
uint32_t nlen;
IF_FW_DEBUG(
strbuf_clear(&sbuf);
dump_events(&sbuf, e->mask);
FW_DEBUG("wd %i :: %s :: %s", e->wd, e->name, sbuf.start);
)
if(!rec) {
goto skip;
if(UNLIKELY(misalign)) {
IF_FW_DEBUG(log_warn("inotify_event pointer %p misaligned by %u",
buf + i, (uint)misalign));
nlen = filewatch_process_event_misaligned(
bufsize - i, buf + i
IF_FW_DEBUG(, &sbuf)
);
} else {
nlen = filewatch_process_event(
CASTPTR_ASSUME_ALIGNED(buf + i, struct inotify_event)
IF_FW_DEBUG(, &sbuf)
);
}
for(DirWatch *dw = rec->dirwatch_list; dw; dw = dw->next) {
if(dw->wd != e->wd) {
continue;
}
FW_DEBUG("Match dir %s", dw->path);
if(e->mask & IN_ISDIR) {
if(e->mask & (IN_MOVE_SELF | IN_DELETE_SELF | IN_IGNORED)) {
dirwatch_invalidate(dw);
}
continue;
}
for(FileWatch *fw = dw->filewatch_list; fw; fw = fw->next) {
if(strcmp(fw->filename, e->name)) {
FW_DEBUG("* %p %s != %s", fw, fw->filename, e->name);
continue;
}
FW_DEBUG("Match file %s/%s", dw->path, fw->filename);
if(e->mask & (IN_DELETE | IN_MOVED_FROM)) {
fw->deleted = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
} else if(e->mask & (IN_CREATE | IN_MOVED_TO)) {
fw->deleted = false;
fw->updated = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
} else if(e->mask & (IN_CLOSE_WRITE | IN_MODIFY)) {
fw->updated = true;
ht_filewatchset_set(&FW.updated_watches, fw, HT_EMPTY);
}
}
}
skip:
i += sizeof(*e) + e->len;
i += sizeof(struct inotify_event) + nlen;
}
IF_FW_DEBUG(