main.c: Add -m command line option to open a named pipe

This write-only named pipe is meant to inform other processes about
files that have been added/removed to/from the user/ directory.
The syntax is line-oriented and is described below.

For added files:
+<space ...><path><LF>

For removed files:
-<space ...><path><LF>

Paths shall always be absolute.

Examples:

+ /home/test/db/user/alice/a picture.jpg
- /home/test/db/user/bob/essay.txt

As reported above, this feature has been made completely optional so as
not to introduce breaking changes. A new command line option, namely -m,
is required to enable this feature.

1 files changed, 288 insertions, 47 deletions

diff --git a/main.c b/main.c
index e0e881e..d56927a 100644
--- a/main.c
+++ b/main.c
@@ -7,6 +7,7 @@
 #endif
 
 #include "auth.h"
+#include "crealpath.h"
 #include "cftw.h"
 #include "hex.h"
 #include "page.h"
@@ -39,6 +40,14 @@ struct form
     char *key, *value;
 };
 
+struct user_args
+{
+    struct auth *a;
+    struct dynstr d;
+    int fd;
+    bool fifo;
+};
+
 static struct handler *handler;
 
 static int redirect(struct http_response *const r)
@@ -60,9 +69,9 @@ static int redirect(struct http_response *const r)
 static int serve_index(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
 
-    if (auth_cookie(a, &p->cookie))
+    if (auth_cookie(ua->a, &p->cookie))
         return page_login(r);
 
     return redirect(r);
@@ -72,8 +81,8 @@ static int serve_style(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    struct auth *const a = user;
-    const char *const dir = auth_dir(a);
+    const struct user_args *const ua = user;
+    const char *const dir = auth_dir(ua->a);
     struct dynstr d;
 
     dynstr_init(&d);
@@ -301,7 +310,7 @@ static int login(const struct http_payload *const pl,
     int ret = -1;
     size_t n = 0;
     struct form *forms = NULL;
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
     char *cookie = NULL;
 
     if ((ret = get_forms(pl, &forms, &n)))
@@ -311,7 +320,7 @@ static int login(const struct http_payload *const pl,
 
         goto end;
     }
-    else if ((ret = check_credentials(a, forms, n, &cookie)))
+    else if ((ret = check_credentials(ua->a, forms, n, &cookie)))
     {
         if (ret < 0)
             fprintf(stderr, "%s: check_credentials failed\n", __func__);
@@ -348,9 +357,9 @@ end:
 static int logout(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
     const struct http_cookie *const c = &p->cookie;
-    const int res = auth_cookie(a, c);
+    const int res = auth_cookie(ua->a, c);
 
     if (res < 0)
     {
@@ -443,8 +452,8 @@ static int getpublic(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    struct auth *const a = user;
-    const char *const adir = auth_dir(a),
+    const struct user_args *const ua = user;
+    const char *const adir = auth_dir(ua->a),
         *const file = p->resource + strlen("/public/");
     struct dynstr d;
 
@@ -717,7 +726,8 @@ static int search(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    const struct auth *const a = user;
+    const struct user_args *const args = user;
+    const struct auth *const a = args->a;
     const char *const username = p->cookie.field, *const root = auth_dir(a);
     struct page_search s = {0};
     int (*f)(struct http_response *);
@@ -778,7 +788,8 @@ end:
 static int share(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
+    const struct auth *const a = ua->a;
 
     if (auth_cookie(a, &p->cookie))
     {
@@ -969,7 +980,8 @@ static int check_length(const unsigned long long len,
 static int getnode(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
+    const struct auth *const a = ua->a;
 
     if (auth_cookie(a, &p->cookie))
     {
@@ -1051,7 +1063,8 @@ end:
 static int getnode_head(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    struct auth *const a = user;
+    const struct user_args *const args = user;
+    const struct auth *const a = args->a;
 
     if (auth_cookie(a, &p->cookie))
     {
@@ -1190,6 +1203,93 @@ static int rename_or_move(const char *const old, const char *const new)
     return res;
 }
 
+static int fifo_writeall(int *const fd, const char *const path,
+    const void *buf, size_t n)
+{
+    if (*fd < 0 && (*fd = open(path, O_WRONLY | O_NONBLOCK)) < 0)
+    {
+        if (errno == ENXIO)
+            return 0;
+        else
+        {
+            fprintf(stderr, "%s: open(2): %s\n", __func__, strerror(errno));
+            return -1;
+        }
+    }
+
+    int ret = -1;
+
+    while (n)
+    {
+        ssize_t res;
+
+again:
+
+        if ((res = write(*fd, buf, n)) < 0)
+        {
+            switch (errno)
+            {
+                case EAGAIN:
+                    /* Fall through. */
+                case EINTR:
+                    goto again;
+
+                case EPIPE:
+                {
+                    ret = 0;
+
+                    if (close(*fd))
+                    {
+                        fprintf(stderr, "%s: close(2): %s\n",
+                            __func__, strerror(errno));
+                        ret = -1;
+                    }
+                    else
+                        *fd = -1;
+
+                    goto end;
+                }
+
+                default:
+                    fprintf(stderr, "%s: write(2): %s\n",
+                        __func__, strerror(errno));
+                    goto end;
+            }
+        }
+
+        n -= res;
+    }
+
+    ret = 0;
+
+end:
+    return ret;
+}
+
+static int fifo_notify_add(int *const fd, const char *const path,
+    const char *const body)
+{
+    static const char header[] = "+ ", lf[] = "\n";
+
+    if (fifo_writeall(fd, path, header, strlen(header)))
+    {
+        fprintf(stderr, "%s: fifo_writeall header failed\n", __func__);
+        return -1;
+    }
+    else if (fifo_writeall(fd, path, body, strlen(body)))
+    {
+        fprintf(stderr, "%s: fifo_writeall body failed\n", __func__);
+        return -1;
+    }
+    else if (fifo_writeall(fd, path, lf, strlen(lf)))
+    {
+        fprintf(stderr, "%s: fifo_writeall lf failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
 static int check_upload_dir(const char *const dir)
 {
     struct stat sb;
@@ -1221,10 +1321,12 @@ static int check_upload_dir(const char *const dir)
 }
 
 static int upload_file(const struct http_post_file *const f,
-    const char *const user, const char *const root, const char *const dir)
+    const char *const user, const char *const root, const char *const dir,
+    struct user_args *const ua)
 {
     int ret = -1;
     struct dynstr dird, d;
+    char *abspath = NULL;
 
     dynstr_init(&dird);
     dynstr_init(&d);
@@ -1256,10 +1358,24 @@ static int upload_file(const struct http_post_file *const f,
         fprintf(stderr, "%s: rename_or_move failed\n", __func__);
         goto end;
     }
+    else if (ua->fifo)
+    {
+        if (!(abspath = crealpath(d.str)))
+        {
+            fprintf(stderr, "%s: crealpath failed\n", __func__);
+            goto end;
+        }
+        else if (fifo_notify_add(&ua->fd, ua->d.str, abspath))
+        {
+            fprintf(stderr, "%s: fifo_notify_add failed\n", __func__);
+            goto end;
+        }
+    }
 
     ret = 0;
 
 end:
+    free(abspath);
     dynstr_free(&dird);
     dynstr_free(&d);
     return ret;
@@ -1317,8 +1433,9 @@ static const char *get_upload_dir(const struct http_post *const po)
 }
 
 static int upload_files(const struct http_payload *const p,
-    struct http_response *const r, const struct auth *const a)
+    struct http_response *const r, struct user_args *const ua)
 {
+    const struct auth *const a = ua->a;
     const struct http_post *const po = &p->u.post;
     const char *const root = auth_dir(a), *const user = p->cookie.field,
         *const dir = get_upload_dir(po);
@@ -1360,7 +1477,7 @@ static int upload_files(const struct http_payload *const p,
 
     for (size_t i = 0; i < po->nfiles; i++)
     {
-        const int ret = upload_file(&po->files[i], user, root, dir);
+        const int ret = upload_file(&po->files[i], user, root, dir, ua);
 
         if (ret < 0)
         {
@@ -1377,9 +1494,9 @@ static int upload_files(const struct http_payload *const p,
 static int upload(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
-    const struct auth *const a = user;
+    struct user_args *const ua = user;
 
-    if (auth_cookie(a, &p->cookie))
+    if (auth_cookie(ua->a, &p->cookie))
     {
         fprintf(stderr, "%s: auth_cookie failed\n", __func__);
         return page_forbidden(r);
@@ -1394,14 +1511,15 @@ static int upload(const struct http_payload *const p,
         return 0;
     }
 
-    return upload_files(p, r, a);
+    return upload_files(p, r, ua);
 }
 
 static int createdir(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
+    const struct auth *const a = ua->a;
     struct dynstr d, userd;
     struct form *forms = NULL;
     size_t n = 0;
@@ -1605,14 +1723,14 @@ static int confirm_rm(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    struct auth *const a = user;
+    const struct user_args *const ua = user;
     struct form *forms = NULL;
     const char **items = NULL;
     size_t n = 0;
     int (*f)(struct http_response *);
     struct page_rm rm = {0};
 
-    if (auth_cookie(a, &p->cookie))
+    if (auth_cookie(ua->a, &p->cookie))
     {
         fprintf(stderr, "%s: auth_cookie failed\n", __func__);
         ret = page_forbidden(r);
@@ -1676,36 +1794,82 @@ static const char *find_rm_dir(const struct form *const forms, const size_t n,
     return dir;
 }
 
+static int fifo_notify_remove(int *const fd, const char *const path,
+    const char *const body)
+{
+    static const char header[] = "- ", lf[] = "\n";
+
+    if (fifo_writeall(fd, path, header, strlen(header)))
+    {
+        fprintf(stderr, "%s: fifo_writeall header failed\n", __func__);
+        return -1;
+    }
+    else if (fifo_writeall(fd, path, body, strlen(body)))
+    {
+        fprintf(stderr, "%s: fifo_writeall body failed\n", __func__);
+        return -1;
+    }
+    else if (fifo_writeall(fd, path, lf, strlen(lf)))
+    {
+        fprintf(stderr, "%s: fifo_writeall lf failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
 static int rm_dir_contents(const char *const fpath,
     const struct stat *const sb, bool *const done, void *const user)
 {
+    int ret = -1;
+    struct user_args *const ua = user;
+    char *abspath = NULL;
+
     if (S_ISDIR(sb->st_mode) && rmdir(fpath))
     {
         fprintf(stderr, "%s: rmdir(2) %s: %s\n",
             __func__, fpath, strerror(errno));
-        return -1;
+        goto end;
     }
     else if (S_ISREG(sb->st_mode) && remove(fpath))
     {
         fprintf(stderr, "%s: remove(3) %s: %s\n",
             __func__, fpath, strerror(errno));
-        return -1;
+        goto end;
+    }
+    else if (ua->fifo)
+    {
+        if (!(abspath = crealpath(fpath)))
+        {
+            fprintf(stderr, "%s: crealpath failed\n", __func__);
+            goto end;
+        }
+        else if (fifo_notify_remove(&ua->fd, ua->d.str, abspath))
+        {
+            fprintf(stderr, "%s: fifo_notify_remove failed\n", __func__);
+            goto end;
+        }
     }
 
-    return 0;
+    ret = 0;
+
+end:
+    free(abspath);
+    return ret;
 }
 
-static int rmdir_r(const char *const path)
+static int rmdir_r(struct user_args *const ua, const char *const path)
 {
     int ret = -1;
     DIR *const d = opendir(path);
+    char *abspath = NULL;
 
     if (!d)
     {
         fprintf(stderr, "%s: opendir(3): %s\n", __func__, strerror(errno));
         goto end;
     }
-    else if (cftw(path, rm_dir_contents, NULL))
+    else if (cftw(path, rm_dir_contents, ua))
     {
         fprintf(stderr, "%s: rm_dir_contents failed\n", __func__);
         goto end;
@@ -1716,6 +1880,19 @@ static int rmdir_r(const char *const path)
             __func__, path, strerror(errno));
         goto end;
     }
+    else if (ua->fifo)
+    {
+        if (!(abspath = crealpath(path)))
+        {
+            fprintf(stderr, "%s: crealpath failed\n", __func__);
+            goto end;
+        }
+        else if (fifo_notify_remove(&ua->fd, ua->d.str, abspath))
+        {
+            fprintf(stderr, "%s: fifo_notify_remove failed\n", __func__);
+            goto end;
+        }
+    }
 
     ret = 0;
 
@@ -1726,10 +1903,12 @@ end:
         ret = -1;
     }
 
+    free(abspath);
     return ret;
 }
 
-static int rm_item(const char *const root, const char *const item)
+static int rm_item(struct user_args *const ua, const char *const root,
+    const char *const item)
 {
     int ret = -1;
     struct stat sb;
@@ -1754,15 +1933,23 @@ static int rm_item(const char *const root, const char *const item)
 
         goto end;
     }
-    else if (S_ISDIR(sb.st_mode) && rmdir_r(d.str))
+    else if (S_ISDIR(sb.st_mode) && rmdir_r(ua, d.str))
     {
         fprintf(stderr, "%s: rmdir_r failed\n", __func__);
         goto end;
     }
-    else if (S_ISREG(sb.st_mode) && remove(d.str))
+    else if (S_ISREG(sb.st_mode))
     {
-        fprintf(stderr, "%s: remove(3): %s\n", __func__, strerror(errno));
-        goto end;
+        if (remove(d.str))
+        {
+            fprintf(stderr, "%s: remove(3): %s\n", __func__, strerror(errno));
+            goto end;
+        }
+        else if (ua->fifo && fifo_notify_remove(&ua->fd, ua->d.str, d.str))
+        {
+            fprintf(stderr, "%s: fifo_notify_remove failed\n", __func__);
+            goto end;
+        }
     }
 
     ret = 0;
@@ -1772,8 +1959,8 @@ end:
     return ret;
 }
 
-static int do_rm(const struct form *const forms, const size_t n,
-    const char *const dir)
+static int do_rm(struct user_args *const ua, const struct form *const forms,
+    const size_t n, const char *const dir)
 {
     for (size_t i = 0; i < n; i++)
     {
@@ -1788,7 +1975,7 @@ static int do_rm(const struct form *const forms, const size_t n,
                 fprintf(stderr, "%s: invalid path %s\n", __func__, path);
                 return 1;
             }
-            else if (rm_item(dir, f->value))
+            else if (rm_item(ua, dir, f->value))
             {
                 fprintf(stderr, "%s: rm_item failed\n", __func__);
                 return -1;
@@ -1803,7 +1990,8 @@ static int rm(const struct http_payload *const p,
     struct http_response *const r, void *const user)
 {
     int ret = -1;
-    struct auth *const a = user;
+    struct user_args *const ua = user;
+    const struct auth *const a = ua->a;
     struct form *forms = NULL;
     size_t n = 0;
     const struct http_cookie *const c = &p->cookie;
@@ -1854,7 +2042,7 @@ static int rm(const struct http_payload *const p,
         fprintf(stderr, "%s: dynstr_append failed\n", __func__);
         goto end;
     }
-    else if ((ret = do_rm(forms, n, userdir.str)))
+    else if ((ret = do_rm(ua, forms, n, userdir.str)))
     {
         if (ret < 0)
             fprintf(stderr, "%s: do_rm failed\n", __func__);
@@ -1891,12 +2079,12 @@ end:
 
 static void usage(char *const argv[])
 {
-    fprintf(stderr, "%s [-t tmpdir] [-p port] dir\n", *argv);
+    fprintf(stderr, "%s [-F] [-t tmpdir] [-p port] dir\n", *argv);
 }
 
 static int parse_args(const int argc, char *const argv[],
     const char **const dir, unsigned short *const port,
-    const char **const tmpdir)
+    const char **const tmpdir, bool *const fifo)
 {
     const char *const envtmp = getenv("TMPDIR");
     int opt;
@@ -1905,10 +2093,14 @@ static int parse_args(const int argc, char *const argv[],
     *port = 0;
     *tmpdir = envtmp ? envtmp : "/tmp";
 
-    while ((opt = getopt(argc, argv, "t:p:")) != -1)
+    while ((opt = getopt(argc, argv, "Ft:p:")) != -1)
     {
         switch (opt)
         {
+            case 'F':
+                *fifo = true;
+                break;
+
             case 't':
                 *tmpdir = optarg;
                 break;
@@ -2185,24 +2377,67 @@ static int init_signals(void)
     return 0;
 }
 
+static int ensure_fifo(const char *const dir, struct user_args *const ua)
+{
+    int ret = -1;
+
+    if (dynstr_append(&ua->d, "%s/slcl.fifo", dir))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (mkfifo(ua->d.str, S_IRUSR | S_IWUSR))
+    {
+        fprintf(stderr, "%s: mkfifo(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    return ret;
+}
+
+static int user_args_free(struct user_args *const ua)
+{
+    int ret = 0;
+
+    if (ua)
+    {
+        if (ua->d.str && remove(ua->d.str))
+        {
+            fprintf(stderr, "%s: remove(3): %s\n", __func__, strerror(errno));
+            ret = -1;
+        }
+
+        auth_free(ua->a);
+        dynstr_free(&ua->d);
+    }
+
+    return ret;
+}
+
 int main(int argc, char *argv[])
 {
     int ret = EXIT_FAILURE;
-    struct auth *a = NULL;
     const char *dir, *tmpdir;
     unsigned short port;
+    struct user_args ua = {.fd = -1};
 
-    if (parse_args(argc, argv, &dir, &port, &tmpdir)
+    dynstr_init(&ua.d);
+
+    if (parse_args(argc, argv, &dir, &port, &tmpdir, &ua.fifo)
         || init_dirs(dir)
         || ensure_style(dir)
-        || !(a = auth_alloc(dir)))
+        || !(ua.a = auth_alloc(dir))
+        || (ua.fifo && ensure_fifo(dir, &ua)))
         goto end;
 
     const struct handler_cfg cfg =
     {
         .length = check_length,
         .tmpdir = tmpdir,
-        .user = a,
+        .user = ua.a,
         .post =
         {
             /* Arbitrary limit. */
@@ -2215,7 +2450,7 @@ int main(int argc, char *argv[])
     unsigned short outport;
 
     if (!(handler = handler_alloc(&cfg))
-        || add_urls(handler, a)
+        || add_urls(handler, &ua)
         || init_signals()
         || handler_listen(handler, port, &outport))
         goto end;
@@ -2231,7 +2466,13 @@ int main(int argc, char *argv[])
     ret = EXIT_SUCCESS;
 
 end:
-    auth_free(a);
     handler_free(handler);
+
+    if (user_args_free(&ua))
+    {
+        fprintf(stderr, "%s: user_args_free failed\n", __func__);
+        ret = EXIT_FAILURE;
+    }
+
     return ret;
 }