reader: read and parse a BMP headers

we retrieve valuable information such as the data offset, the width and
the height of the picture which path is passed as parameter.

Signed-off-by: Olivier Gayot <duskcoder@gmail.com>

4 files changed, 668 insertions, 0 deletions

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..d7f1051
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,339 @@
+GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc., <http://fsf.org/>
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
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+
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+    {description}
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+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 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 General Public License for more details.
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+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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+
+This General Public License does not permit incorporating your program into
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+Public License instead of this License.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5724b71
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,46 @@
+## Copyright (C) 2014 Olivier Gayot <duskcoder@gmail.com>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 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 General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License along
+## with this program; if not, write to the Free Software Foundation, Inc.,
+## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+CC       ?= gcc
+CFLAGS   += -W -Wall -std=gnu99 -Wextra
+CFLAGS   += -D _XOPEN_SOURCE -D _DEFAULT_SOURCE
+NAME      = stegmp
+SRC       = stegmp.c
+
+all: depend $(NAME)
+
+depend: .depend
+
+.depend: $(SRC)
+	@$(RM) .depend
+	@$(CC) $(CFLAGS) -MM $^ > .depend
+
+include .depend
+
+OBJ     = $(SRC:.c=.o)
+
+$(NAME): $(OBJ)
+	$(CC) -o $@ $^ $(LDFLAGS)
+
+clean:
+	$(RM) $(OBJ)
+
+fclean: clean
+	$(RM) $(NAME)
+
+re: fclean all
+
+.PHONY: all depend clean fclean all re
diff --git a/bmp.h b/bmp.h
new file mode 100644
index 0000000..a4d794b
--- /dev/null
+++ b/bmp.h
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2014 Olivier Gayot <duskcoder@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef BMP_H
+#define BMP_H
+
+#include <endian.h>
+
+#include <stdint.h>
+
+struct packed_bmp_header {
+    uint16_t magic;
+    uint32_t bmp_size;
+    uint16_t reserved;
+    uint16_t reserved2;
+    uint32_t data_offset;
+} __attribute__((packed));
+
+struct bitmap {
+    uint32_t size;
+    uint32_t data_offset;
+    uint32_t width;
+    uint32_t height;
+    uint16_t bpp;
+};
+
+/* Windows BITMAPINFOHEADER */
+struct bitmap_info_header {
+    uint32_t header_size;
+    uint32_t bmp_width;
+    uint32_t bmp_height;
+    uint16_t planes;
+    uint16_t bpp;
+    uint32_t compression;
+    uint32_t img_size;
+    uint32_t horizontal_res;
+    uint32_t vertical_res;
+    uint32_t palette;
+    uint32_t important_colors;
+} __attribute((packed));
+
+enum {
+#if __BYTE_ORDER == __BIG_ENDIAN
+    BMP_MAGIC_BM = 0x424D,
+    BMP_MAGIC_BA = 0x4241,
+    BMP_MAGIC_CI = 0x4349,
+    BMP_MAGIC_CP = 0x4350,
+    BMP_MAGIC_IC = 0x4943,
+    BMP_MAGIC_PT = 0x5054,
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+    BMP_MAGIC_BM = 0x4D42,
+    BMP_MAGIC_BA = 0x4142,
+    BMP_MAGIC_CI = 0x4943,
+    BMP_MAGIC_CP = 0x5043,
+    BMP_MAGIC_IC = 0x4349,
+    BMP_MAGIC_PT = 0x5450,
+#endif
+};
+
+enum {
+    /* bmp header */
+    BMP_ESUCCESS,
+    BMP_ENOTBMP,
+    BMP_ENOTSUPP,
+
+    BMP_EINVALSIZ,
+
+    BMP_EINVALBPP,
+
+    BMP_ERRNO_COUNT,
+};
+
+const char *bmp_error_string[] = {
+    [BMP_ESUCCESS] = "Success",
+    [BMP_ENOTBMP] = "File is not a BMP",
+    [BMP_ENOTSUPP] = "File format not supported",
+    [BMP_EINVALSIZ] = "Inconsistent file size",
+    [BMP_EINVALBPP] = "Invalid BPP value",
+};
+
+int bmp_errno = BMP_ESUCCESS;
+
+static inline const char *bmp_strerror(int err)
+{
+    return bmp_error_string[err];
+}
+
+#endif /* BMP_H */
diff --git a/stegmp.c b/stegmp.c
new file mode 100644
index 0000000..b1f42a8
--- /dev/null
+++ b/stegmp.c
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2014 Olivier Gayot <duskcoder@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <string.h>
+#include <stdio.h>
+
+#include "bmp.h"
+
+static int stegmp_parse_windows_bitmap_info_header(const unsigned char *addr,
+        size_t size, struct bitmap *bmpp)
+{
+    struct bitmap_info_header info_header;
+
+    if (size < sizeof(typeof(info_header))) {
+        bmp_errno = BMP_EINVALSIZ;
+        return -1;
+    }
+
+    info_header = *((typeof(info_header) *)addr);
+
+    switch (info_header.bpp) {
+        case 8:
+        case 16:
+        case 24:
+        case 32:
+            bmpp->bpp = info_header.bpp;
+                break;
+        default:
+            bmp_errno = BMP_EINVALBPP;
+            return -1;
+    }
+
+    /* TODO check the compression type */
+
+    bmpp->width = info_header.bmp_width;
+    bmpp->height = info_header.bmp_height;
+
+    return 0;
+}
+
+/* guess which type of DIB header it is and handle it or not */
+static int stegmp_parse_dib_header(const unsigned char *addr, size_t size,
+        struct bitmap *bmpp)
+{
+    uint32_t dib_size;
+
+    if (size < sizeof(typeof(dib_size))) {
+        bmp_errno = BMP_EINVALSIZ;
+        return -1;
+    }
+
+    dib_size = *((typeof(dib_size) *)addr);
+
+    switch (dib_size) {
+        case 12:
+        case 52:
+        case 56:
+        case 64:
+        case 108:
+        case 124:
+            bmp_errno = BMP_ENOTSUPP;
+            return -1;
+
+        case 40:
+            return stegmp_parse_windows_bitmap_info_header(addr, size, bmpp);
+
+        default:
+            bmp_errno = BMP_ENOTBMP;
+            return -1;
+    }
+}
+
+/* parse the main header of the bmp file */
+static int stegmp_parse_headers(const unsigned char *addr, size_t orig_size,
+        struct bitmap *bmpp)
+{
+    struct packed_bmp_header packed_header;
+
+    if (orig_size < sizeof(packed_header)) {
+        bmp_errno = BMP_ENOTBMP;
+        return -1;
+    }
+
+    packed_header = *((typeof(packed_header) *)addr);
+
+    switch (packed_header.magic) {
+        case BMP_MAGIC_BM:
+            break;
+
+        case BMP_MAGIC_BA:
+        case BMP_MAGIC_CI:
+        case BMP_MAGIC_CP:
+        case BMP_MAGIC_IC:
+        case BMP_MAGIC_PT:
+            bmp_errno = BMP_ENOTSUPP;
+            return -1;
+        default:
+            bmp_errno = BMP_ENOTBMP;
+            return -1;
+    }
+
+    if (packed_header.bmp_size != orig_size) {
+        bmp_errno = BMP_EINVALSIZ;
+        return -1;
+    }
+
+    bmpp->data_offset = packed_header.data_offset;
+    bmpp->size = packed_header.bmp_size;
+
+    stegmp_parse_dib_header(addr + sizeof(packed_header), orig_size, bmpp);
+
+    return 0;
+}
+
+static int stegmp(const char *filename)
+{
+    void *addr;
+    struct stat stat;
+    struct bitmap bmp;
+    FILE *fh = fopen(filename, "r+");
+
+    if (fh == NULL) {
+        fprintf(stderr, "%s: %m\n", filename);
+        return -1;
+    }
+
+    fstat(fileno(fh), &stat);
+    addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
+            fileno(fh), 0);
+
+    if (addr == MAP_FAILED) {
+        fprintf(stderr, "%s: %m\n", filename);
+        fclose(fh);
+        return -1;
+    }
+
+    /* retrieve the required information (i.e. width, height, bpp .. ) */
+    if (stegmp_parse_headers(addr, stat.st_size, &bmp) >= 0) {
+        /* TODO */
+    } else {
+        fprintf(stderr, "unable to parse headers: %s\n",
+                bmp_strerror(bmp_errno));
+    }
+
+    munmap(addr, stat.st_size);
+    fclose(fh);
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    /* we need a file passed as argument since we want to map it */
+    if (argc < 2) {
+        fprintf(stderr, "usage: %s BMP\n", argv[0]);
+        return -1;
+    }
+
+    return stegmp(argv[1]);
+}