Add PNG stream splitter

I don't know, somehow this is easier than having gfxx care about where
it's writing to.

3 files changed, 77 insertions, 1 deletions

diff --git a/bin/.gitignore b/bin/.gitignore
index ae5a47b8..cb1d47f3 100644
--- a/bin/.gitignore
+++ b/bin/.gitignore
@@ -7,6 +7,7 @@ hnel
 pbcopy
 pbd
 pbpaste
+pngs
 wake
 xx
 jrp
diff --git a/bin/Makefile b/bin/Makefile
index 708860c6..44454bff 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -1,4 +1,4 @@
-ANY_BINS = atch dtch gfxx hnel pbcopy pbd pbpaste wake xx
+ANY_BINS = atch dtch gfxx hnel pbcopy pbd pbpaste pngs wake xx
 BSD_BINS = jrp klon typo watch
 LIN_BINS = bri fbatt fbclock
 ALL_BINS = $(ANY_BINS) $(BSD_BINS) $(LIN_BINS)
diff --git a/bin/pngs.c b/bin/pngs.c
new file mode 100644
index 00000000..6c26c303
--- /dev/null
+++ b/bin/pngs.c
@@ -0,0 +1,75 @@
+/* Copyright (c) 2018, June McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static const uint8_t SIGNATURE[] = { 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n' };
+static const uint8_t IEND[] = { 'I', 'E', 'N', 'D' };
+
+static unsigned counter;
+static char path[FILENAME_MAX];
+static int fd;
+
+static void next(const char *prefix) {
+    if (counter++) {
+        int error = close(fd);
+        if (error) err(EX_IOERR, "%s", path);
+    }
+    snprintf(path, sizeof(path), "%s%04u.png", prefix, counter);
+    fd = open(path, O_WRONLY | O_CREAT | O_EXCL, 0644);
+    if (fd < 0) err(EX_CANTCREAT, "%s", path);
+    printf("%s\n", path);
+}
+
+static void writeAll(const uint8_t *buf, size_t size) {
+    while (size) {
+        ssize_t writeSize = write(fd, buf, size);
+        if (writeSize < 0) err(EX_IOERR, "%s", path);
+        buf += writeSize;
+        size -= writeSize;
+    }
+}
+
+int main(int argc, char *argv[]) {
+    const char *prefix = (argc > 1) ? argv[1] : "";
+
+    for (;;) {
+        uint8_t buf[4096];
+        ssize_t size = read(STDIN_FILENO, buf, sizeof(buf));
+        if (size < 0) err(EX_IOERR, "read");
+        if (!size) return EX_OK;
+
+        const uint8_t *signature = memmem(buf, size, SIGNATURE, sizeof(SIGNATURE));
+        if (signature) {
+            writeAll(buf, signature - buf);
+            next(prefix);
+            writeAll(signature, size - (signature - buf));
+        } else {
+            const uint8_t *iend = memmem(buf, size, IEND, sizeof(IEND));
+            if (iend && iend - buf < size - 8) {
+                warnx("trailing data, a PNG may be skipped");
+            }
+            writeAll(buf, size);
+        }
+    }
+}