multi-threaded tabfs.c

3 files changed, 381 insertions, 132 deletions

diff --git a/extension/background.js b/extension/background.js
index 1b1cad0..370e106 100644
--- a/extension/background.js
+++ b/extension/background.js
@@ -632,7 +632,7 @@ async function onMessage(req) {
     // timeout is very useful because some operations just hang
     // (like trying to take a screenshot, until the tab is focused)
     didTimeout = true; console.error('timeout');
-    port.postMessage({ op: req.op, error: unix.ETIMEDOUT });
+    port.postMessage({ id: req.id, op: req.op, error: unix.ETIMEDOUT });
   }, 1000);
 
   /* console.time(req.op + ':' + req.path);*/
@@ -654,6 +654,7 @@ async function onMessage(req) {
     clearTimeout(timeout);
 
     console.log('resp', response);
+    response.id = req.id;
     port.postMessage(response);
   }
 };
diff --git a/fs/Makefile b/fs/Makefile
index 97ca01a..37f0f3d 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -7,25 +7,26 @@ OSXFUSE_ROOT = /usr/local
 # Root for libraries from FreeBSD's ports
 FREEBSD_ROOT = /usr/local
 
-CFLAGS_EXTRA = -DFUSE_USE_VERSION=26 -D_FILE_OFFSET_BITS=64 -Wall -Wno-unused-function -g
+CFLAGS ?= -O2
+CFLAGS_EXTRA = -DFUSE_USE_VERSION=26 -D_FILE_OFFSET_BITS=64 -Wall -Wextra -Wno-unused-result -g
 
 ifeq ($(shell uname -s),Linux)
 	CFLAGS += $(CFLAGS_EXTRA)
-	LIBS = -lfuse
+	LIBS = -lfuse -pthread
 endif
 ifeq ($(shell uname -s),Darwin)
-	CFLAGS = -I$(OSXFUSE_ROOT)/include/osxfuse/fuse -L$(OSXFUSE_ROOT)/lib -D_DARWIN_USE_64_BIT_INODE $(CFLAGS_EXTRA)
+	CFLAGS += -I$(OSXFUSE_ROOT)/include/osxfuse/fuse -L$(OSXFUSE_ROOT)/lib -D_DARWIN_USE_64_BIT_INODE $(CFLAGS_EXTRA)
 	LIBS = -losxfuse
 endif
 ifeq ($(shell uname -s),FreeBSD)
 	CFLAGS += -L$(FREEBSD_ROOT)/lib -I$(FREEBSD_ROOT)/include $(CFLAGS_EXTRA)
-	LIBS = -lfuse
+	LIBS = -lfuse -pthread
 endif
 
 all: $(TARGETS)
 
 tabfs: tabfs.c
-	cc $(CFLAGS) -o $@ $^ $(LIBS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
 
 clean:
 	rm -f $(TARGETS) *.o
@@ -34,3 +35,4 @@ clean:
 unmount:
 	killall -9 tabfs || true
 	diskutil unmount force mnt || true
+	fusermount -u mnt || true
diff --git a/fs/tabfs.c b/fs/tabfs.c
index fecec22..d00e96c 100644
--- a/fs/tabfs.c
+++ b/fs/tabfs.c
@@ -1,231 +1,477 @@
-// This file should rarely need to be changed. (which is intentional,
-// because it is a pain to program here, it's a pain to recompile and
-// reload it, and it's a pain to debug it.)  Most of the real meat of
-// TabFS is on the extension side, not here.
-
-#include <errno.h>
-#include <fcntl.h>
-#include <string.h>
-#include <unistd.h>
 #include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
 #include <pthread.h>
+#include <string.h>
+#include <errno.h>
+#include <stdint.h>
+#include <assert.h>
+
 #include <fuse.h>
 
 #include "vendor/frozen.h"
 #include "vendor/frozen.c"
 
-FILE* l;
+#define eprintln(fmt, ...) fprintf(stderr, fmt "\n", ##__VA_ARGS__)
+
+// protects:
+// - writing to stdout
+// - the "waiters" global
+static pthread_mutex_t write_lock = PTHREAD_MUTEX_INITIALIZER;
+
+struct resumedata {
+    unsigned int id;
+    int msgpipe[2];
+    void *data;
+    size_t size;
+};
+
+static struct resumedata **waiters;
+static size_t numwaiters;
+
+static void read_or_die(int fd, void *buf, size_t sz) {
+    size_t sofar = 0;
+    while (sofar < sz) {
+        ssize_t rv = read(fd, (char *)buf+sofar, sz-sofar);
+        if (rv == -1) {
+            if (errno == EINTR || errno == EAGAIN) continue;
+            perror("read error");
+            exit(1);
+        }
+        if (rv == 0) exit(1);
+        sofar += (size_t)rv;
+    }
+}
+static void write_or_die(int fd, void *buf, size_t sz) {
+    size_t sofar = 0;
+    while (sofar < sz) {
+        ssize_t rv = write(fd, (char *)buf+sofar, sz-sofar);
+        if (rv == -1) {
+            if (errno == EINTR || errno == EAGAIN) continue;
+            perror("write error");
+            exit(1);
+        }
+        if (rv == 0) exit(1);
+        sofar += (size_t)rv;
+    }
+}
+
+// documented somewhere in https://developer.chrome.com/docs/apps/nativeMessaging/
+#define MAX_MESSAGE_SIZE (1024*1024)
 
-static void send_request(const char *fmt, ...) {
-    va_list args; va_start(args, fmt);
+static int do_exchange(unsigned int id,
+                       char **datap, size_t *sizep,
+                       const char *fmt, ...) {
+    *datap = NULL;
+    *sizep = 0;
 
-    char request_data[1024*1024]; // max size of native->Chrome message
-    struct json_out out = JSON_OUT_BUF(request_data, sizeof(request_data));
-    unsigned int request_len = json_vprintf(&out, fmt, args);
+    char jsonbuf[MAX_MESSAGE_SIZE];
+    struct json_out out = JSON_OUT_BUF(jsonbuf, sizeof(jsonbuf));
 
+    va_list args;
+    va_start(args, fmt);
+     size_t request_size = (size_t)json_vprintf(&out, fmt, args);
     va_end(args);
+    if (request_size > sizeof(jsonbuf)) {
+        eprintln("warning: request too big to send (%zu > %zu)",
+            request_size, sizeof(jsonbuf));
+        return -EMSGSIZE;
+    }
+
+    struct resumedata mydata = {
+        .id = id,
+        .msgpipe = {-1, -1},
+        .data = NULL,
+        .size = 0,
+    };
+    if (-1 == pipe(mydata.msgpipe)) {
+        perror("exchange: pipe");
+        return -EIO;
+    }
+
+    pthread_mutex_lock(&write_lock);
 
-    write(1, (char *) &request_len, 4); // stdout
-    unsigned int bytes_written = 0;
-    while (bytes_written < request_len) {
-        bytes_written += write(1, request_data, request_len);
+    uint32_t size_4bytes = request_size;
+
+    write_or_die(STDOUT_FILENO, &size_4bytes, sizeof(size_4bytes));
+    write_or_die(STDOUT_FILENO, jsonbuf, request_size);
+
+    waiters = realloc(waiters, (numwaiters+1)*sizeof(*waiters));
+    waiters[numwaiters] = &mydata;
+    numwaiters += 1;
+
+    pthread_mutex_unlock(&write_lock);
+
+    char c;
+    read_or_die(mydata.msgpipe[0], &c, 1);
+
+    close(mydata.msgpipe[0]);
+    close(mydata.msgpipe[1]);
+
+    int err;
+    if (1 == json_scanf(mydata.data, mydata.size, "{error: %d}", &err)) {
+        free(mydata.data);
+        return -err;
     }
-    /* fprintf(l, "req[%s]\n", request_data); fflush(l); */
+
+    *datap = mydata.data;
+    *sizep = mydata.size;
+
+    return 0;
 }
 
-static int await_response(char **resp) {
-    unsigned int response_len;
-    read(0, (char *) &response_len, 4); // stdin
-    char *response_data = malloc(response_len);
-    unsigned int bytes_read = 0;
-    while (bytes_read < response_len) {
-        bytes_read += read(0, response_data + bytes_read, response_len);
+static void *reader_main(void *ud) {
+    (void)ud;
+    for (;;) {
+        uint32_t size_4bytes;
+        read_or_die(STDIN_FILENO, &size_4bytes, sizeof(size_4bytes));
+        size_t insize = size_4bytes;
+
+        char *data = malloc(insize);
+        read_or_die(STDIN_FILENO, data, insize);
+
+        unsigned int id;
+        if (1 != json_scanf(data, insize, "{id: %u}", &id)) {
+            eprintln("reader: warning: got a message without an id, ignoring");
+            free(data);
+            continue;
+        }
+
+        pthread_mutex_lock(&write_lock);
+        int found = 0;
+        unsigned int i = numwaiters;
+        while (i --> 0) {
+            if (waiters[i]->id == id) {
+                char c = '!';
+                waiters[i]->data = data;
+                waiters[i]->size = insize;
+                write_or_die(waiters[i]->msgpipe[1], &c, 1);
+                memmove(&waiters[i], &waiters[i+1],
+                    (numwaiters-(i+1))*sizeof(*waiters));
+                numwaiters -= 1;
+                found = 1;
+                break;
+            }
+        }
+        if (!found) {
+            eprintln("reader: warning: got a message for nonexistent waiter %u", id);
+            free(data);
+        }
+        pthread_mutex_unlock(&write_lock);
     }
-    /* fprintf(l, "resp(%d; expected %d)[%s]\n", bytes_read, response_len, response_data); fflush(l); */
-    if (response_data == NULL) {
-        // Connection is dead.
-        *resp = "{ \"error\": 5 }";
-        return strlen(*resp);
+    return NULL;
+}
+
+static int count_fmt_args(const char *s) {
+    int cnt = 0;
+    for (; *s; s++) {
+        if (*s == '%') {
+            if (*(s+1) != '%') cnt++;
+            else s++;
+        }
     }
+    return cnt;
+}
+
+#define exchange_json(datap, sizep, keys_fmt, ...) \
+    do { \
+        unsigned int id = pthread_self(); \
+        int req_rv = do_exchange(id, datap, sizep, \
+            "{id: %u, " keys_fmt "}", \
+            id, ##__VA_ARGS__); \
+        if (req_rv != 0) return req_rv; \
+    } while (0)
 
-    *resp = response_data;
-    return response_len;
-}
-
-#define receive_response(fmt, ...)                                      \
-    do {                                                                \
-        char *resp; int resp_len;                                       \
-        resp_len = await_response(&resp);                               \
-        if (!resp_len) return -EIO;                                     \
-                                                                        \
-        int err;                                                        \
-        if (json_scanf(resp, resp_len, "{error: %d}", &err) && err) {   \
-            free(resp); return -err;                                    \
-        }                                                               \
-                                                                        \
-        json_scanf(resp, resp_len, fmt, __VA_ARGS__);                   \
-        free(resp);                                                     \
+#define parse_and_free_response(data, size, keys_fmt, ...) \
+    do { \
+        if (*keys_fmt == '\0') { \
+            /* empty format string, skip the work */ \
+            free(data); data = NULL; \
+        } else { \
+            int num_expected = count_fmt_args(keys_fmt); \
+            int num_scanned = json_scanf(data, size, \
+                "{" keys_fmt "}", \
+                ##__VA_ARGS__); \
+            if (num_scanned == num_expected) { \
+                free(data); data = NULL; \
+            } else { \
+                eprintln("%s: could only parse %d of %d keys!", \
+                    __func__, num_expected, num_scanned); \
+                free(data); data = NULL; \
+                return -EIO; \
+            } \
+        } \
     } while (0)
 
 static int tabfs_getattr(const char *path, struct stat *stbuf) {
-    send_request("{op: %Q, path: %Q}", "getattr", path);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q",
+        "getattr", path);
 
     memset(stbuf, 0, sizeof(struct stat));
-    receive_response("{st_mode: %d, st_nlink: %d, st_size: %d}",
-                     &stbuf->st_mode, &stbuf->st_nlink, &stbuf->st_size);
+    parse_and_free_response(rdata, rsize,
+        "st_mode: %d, st_nlink: %d, st_size: %d",
+        &stbuf->st_mode, &stbuf->st_nlink, &stbuf->st_size);
+
     return 0;
 }
 
 static int tabfs_readlink(const char *path, char *buf, size_t size) {
-    send_request("{op: %Q, path: %Q}", "readlink", path);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q",
+        "readlink", path);
 
-    char *scan_buf; int scan_len;
-    receive_response("{buf: %V}", &scan_buf, &scan_len);
-    memcpy(buf, scan_buf, scan_len < size ? scan_len : size); free(scan_buf);
+    char *scan_buf;
+    int scan_len;
+    parse_and_free_response(rdata, rsize,
+        "buf: %V",
+        &scan_buf, &scan_len);
+
+    // fuse.h:
+    // "If the linkname is too long to fit in the buffer, it should be truncated."
+    if ((size_t)scan_len >= size) scan_len = size-1;
+
+    memcpy(buf, scan_buf, scan_len);
+    buf[scan_len] = '\0';
+
+    free(scan_buf);
 
     return 0;
 }
 
 static int tabfs_open(const char *path, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, flags: %d}", "open", path, fi->flags);
+    char *data;
+    size_t size;
+    exchange_json(&data, &size,
+        "op: %Q, path: %Q, flags: %d",
+        "open", path, fi->flags);
 
-    receive_response("{fh: %d}", &fi->fh);
+    parse_and_free_response(data, size,
+        "fh: %d",
+        &fi->fh);
 
     return 0;
 }
 
-static int
-tabfs_read(const char *path, char *buf, size_t size, off_t offset,
-           struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, size: %d, offset: %d, fh: %d, flags: %d}",
-                 "read", path, size, offset, fi->fh, fi->flags);
+static int tabfs_read(const char *path,
+                      char *buf,
+                      size_t size,
+                      off_t offset,
+                      struct fuse_file_info *fi) {
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, size: %d, offset: %d, fh: %d, flags: %d",
+        "read", path, size, offset, fi->fh, fi->flags);
 
     char *scan_buf; int scan_len;
-    receive_response("{buf: %V}", &scan_buf, &scan_len);
-    memcpy(buf, scan_buf, scan_len < size ? scan_len : size); free(scan_buf);
+    parse_and_free_response(rdata, rsize,
+        "buf: %V",
+        &scan_buf, &scan_len);
+
+    if ((size_t)scan_len > size) scan_len = size;
+    memcpy(buf, scan_buf, scan_len);
+    free(scan_buf);
 
     return scan_len;
 }
 
-static int
-tabfs_write(const char *path, const char *buf, size_t size, off_t offset,
-            struct fuse_file_info *fi) {
-    
-    send_request("{op: %Q, path: %Q, buf: %V, offset: %d, fh: %d, flags: %d}",
-                 "write", path, buf, size, offset, fi->fh, fi->flags);
-
-    int ret; receive_response("{size: %d}", &ret); return ret;
+static int tabfs_write(const char *path,
+                       const char *data,
+                       size_t size,
+                       off_t offset,
+                       struct fuse_file_info *fi) {
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, buf: %V, offset: %d, fh: %d, flags: %d",
+        "write", path, data, size, offset, fi->fh, fi->flags);
+
+    int ret;
+    parse_and_free_response(rdata, rsize,
+        "size: %d",
+        &ret);
+
+    return ret;
 }
 
 static int tabfs_release(const char *path, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, fh: %d}",
-                 "release", path, fi->fh);
+    char *data;
+    size_t size;
+    exchange_json(&data, &size,
+        "op: %Q, path: %Q, fh: %d",
+        "release", path, fi->fh);
+
+    parse_and_free_response(data, size, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
 static int tabfs_opendir(const char *path, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, flags: %d}",
-                 "opendir", path, fi->flags);
-    
-    receive_response("{fh: %d}", &fi->fh);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, flags: %d",
+        "opendir", path, fi->flags);
+
+    parse_and_free_response(rdata, rsize,
+        "fh: %d",
+        &fi->fh);
+
     return 0;
 }
 
-static int
-tabfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
-              off_t offset, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, offset: %d}",
-                 "readdir", path, offset);
+static int tabfs_readdir(const char *path,
+                         void *buf,
+                         fuse_fill_dir_t filler,
+                         off_t offset,
+                         struct fuse_file_info *fi) {
+    (void)fi;
 
-    char *resp; int resp_len;
-    resp_len = await_response(&resp);
-    if (!resp_len) return -EIO;
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, offset: %d",
+        "readdir", path, offset);
 
     struct json_token t;
-    for (int i = 0; json_scanf_array_elem(resp, resp_len, ".entries", i, &t) > 0; i++) {
-        char entry[t.len + 1]; snprintf(entry, t.len + 1, "%.*s", t.len, t.ptr);
+    for (int i = 0; json_scanf_array_elem(rdata, rsize, ".entries", i, &t) > 0; i++) {
+        char entry[t.len+1];
+        memcpy(entry, t.ptr, t.len);
+        entry[t.len] = '\0';
         filler(buf, entry, NULL, 0);
     }
 
-    free(resp);
+    parse_and_free_response(rdata, rsize, "");
+
     return 0;
 }
 
 static int tabfs_releasedir(const char *path, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, fh: %d}",
-                 "releasedir", path, fi->fh);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, fh: %d",
+        "releasedir", path, fi->fh);
+
+    parse_and_free_response(rdata, rsize, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
 static int tabfs_truncate(const char *path, off_t size) {
-    send_request("{op: %Q, path: %Q, size: %d}",
-                 "truncate", path, size);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, size: %d",
+        "truncate", path, size);
+
+    parse_and_free_response(rdata, rsize, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
 static int tabfs_unlink(const char *path) {
-    send_request("{op: %Q, path: %Q}", "unlink", path);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q",
+        "unlink", path);
+
+    parse_and_free_response(rdata, rsize, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
 static int tabfs_mkdir(const char *path, mode_t mode) {
-    send_request("{op: %Q, path: %Q, mode: %d}", "mkdir", path, mode);
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, mode: %d",
+        "mkdir", path, mode);
+
+    parse_and_free_response(rdata, rsize, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
 static int tabfs_create(const char *path, mode_t mode, struct fuse_file_info *fi) {
-    send_request("{op: %Q, path: %Q, mode: %d}", "mkdir", path, mode);
+    (void)fi;
+
+    char *rdata;
+    size_t rsize;
+    exchange_json(&rdata, &rsize,
+        "op: %Q, path: %Q, mode: %d",
+        "mkdir", path, mode);
+
+    parse_and_free_response(rdata, rsize, "");
 
-    receive_response("{}", NULL);
     return 0;
 }
 
-static struct fuse_operations tabfs_filesystem_operations = {
+static const struct fuse_operations tabfs_oper = {
     .getattr  = tabfs_getattr,
     .readlink = tabfs_readlink,
 
-    .open     = tabfs_open,
-    .read     = tabfs_read,
-    .write    = tabfs_write,
-    .release  = tabfs_release,
+    .open    = tabfs_open,
+    .read    = tabfs_read,
+    .write   = tabfs_write,
+    .release = tabfs_release,
 
-    .opendir  = tabfs_opendir,
-    .readdir  = tabfs_readdir,
+    .opendir    = tabfs_opendir,
+    .readdir    = tabfs_readdir,
     .releasedir = tabfs_releasedir,
 
-    .truncate  = tabfs_truncate,
-    .unlink = tabfs_unlink,
+    .truncate = tabfs_truncate,
+    .unlink   = tabfs_unlink,
 
-    .mkdir = tabfs_mkdir,
-    .create = tabfs_create
+    .mkdir  = tabfs_mkdir,
+    .create = tabfs_create,
 };
 
 int main(int argc, char **argv) {
-    char killcmd[1000];
-    sprintf(killcmd, "pgrep tabfs | grep -v %d | xargs kill -9", getpid());
+    (void)argc;
+
+    freopen("log.txt", "a", stderr);
+    setvbuf(stderr, NULL, _IONBF, 0);
+
+    char killcmd[128];
+    sprintf(killcmd, "pgrep tabfs | grep -v %d | xargs kill -9 2>/dev/null", getpid());
     system(killcmd);
-#ifdef __APPLE__
-    system("diskutil umount force mnt > /dev/null");
-#elif __FreeBSD__
-    system("umount -f mnt");
+
+#if defined(__APPLE__)
+    system("diskutil umount force mnt >/dev/null");
+#elif defined(__FreeBSD__)
+    system("umount -f mnt 2>/dev/null");
 #else
-    system("fusermount -u mnt");
+    system("fusermount -u mnt 2>/dev/null");
 #endif
 
-    l = fopen("log.txt", "w");
-    for (int i = 0; i < argc; i++) {
-        fprintf(l, "arg%d: [%s]\n", i, argv[i]); fflush(l);
+    mkdir("mnt", 0755);
+
+    pthread_t thread;
+    int err = pthread_create(&thread, NULL, reader_main, NULL);
+    if (err != 0) {
+        eprintln("pthread_create: %s", strerror(err));
+        exit(1);
     }
-    char* fuse_argv[] = {argv[0], "-odirect_io", "-s", "-f", "mnt"};
-    return fuse_main(5, fuse_argv, &tabfs_filesystem_operations, NULL);
+    pthread_detach(thread);
+
+    char *fuse_argv[] = {
+        argv[0],
+        "-f",
+        "-oauto_unmount",
+        "-odirect_io",
+        "mnt",
+        NULL,
+    };
+    return fuse_main(
+        (sizeof(fuse_argv)/sizeof(*fuse_argv))-1,
+        (char **)&fuse_argv,
+        &tabfs_oper,
+        NULL);
 }