1 files changed, 188 insertions, 0 deletions
diff --git a/format.c b/format.c
new file mode 100644
index 0000000..cbd7265
--- /dev/null
+++ b/format.c
@@ -0,0 +1,188 @@
+#include "format.h"
+#include "gzip.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+struct segment empty_segment = {
+	.start = -1,
+	.end = -1,
+	.description = "No segment selected",
+};
+
+struct segment get_segment(void *mem, size_t len, ssize_t addr) {
+
+	if (addr < 0 || addr >= len) {
+		return empty_segment;
+	}
+
+
+	static char *buf = NULL;
+	if (buf != NULL) {
+		free(buf);
+		buf = NULL;
+	}
+	struct member *header = (struct member*) mem;
+
+	if (addr == 0) {
+		return (struct segment) {
+			.start = 0,
+			.end = 1,
+			.description = "ID1 = 31"
+		};
+	}
+	if (addr == 1) {
+		return (struct segment) {
+			.start = 1,
+			.end = 2,
+			.description = "ID2 = 139",
+		};
+	}
+	if (addr == 2) {
+		return (struct segment) {
+			.start = 2,
+			.end = 3,
+			.description = "CM (Compression Method)\n"
+				"CM = 8 is defalte",
+		};
+	}
+	if (addr == 3) {
+		buf = malloc(1000);
+		buf[0] = '\0';
+		for (int i = 0; i < 5; i++) {
+			if (header->flg & (1 << i)) {
+				strcat(buf, "- ");
+				strcat(buf, flag_str(1<<i));
+				strcat(buf, "\n");
+			}
+		}
+		return (struct segment) {
+			.start = 3,
+			.end = 4,
+			.description = buf,
+		};
+	}
+	if (addr >= 4 && addr < 8) {
+		buf = malloc(1000);
+		sprintf(buf, "Mtime=%i", header->mtime);
+		return (struct segment) {
+			.start = 4,
+			.end = 8,
+			.description = buf,
+		};
+	}
+	if (addr == 8) {
+		return (struct segment) {
+			.start = 8,
+			.end = 9,
+			.description = "XFL",
+		};
+	}
+	if (addr == 9) {
+		buf = malloc(1000);
+		sprintf(buf, "OS: %s\n", os_str(header->os));
+		return (struct segment) {
+			.start = 9,
+			.end = 10,
+			.description = buf,
+		};
+	}
+
+	void *ptr = ((struct member*) mem) + 1;
+
+	if (header->flg & FEXTRA) {
+		uint16_t xlen = *((uint16_t*) ptr);
+		if (mem + addr == ptr || mem + addr == ptr + 1) {
+			return (struct segment) {
+				.start = ptr - mem,
+				.end = ptr - mem + 1,
+				.description = "XLEN",
+			};
+		}
+		ptr = ((uint16_t*) ptr) + 1;
+		// if (mem + addr >= ptr && mem + addr < xlen) {
+		if (ptr - mem + addr < 2) {
+			return (struct segment) {
+				.start = ptr - mem,
+				.end = ptr - mem + xlen,
+				.description = "XLEN bytes of extra data",
+			};
+		}
+		ptr = ((uint8_t*) ptr) + 1 + xlen;
+	}
+
+	if (header->flg & FNAME) {
+		void *c = memchr(ptr, '\0', (ptr - mem) + len);
+		size_t start = ptr - mem;
+		size_t end = c - mem;
+		ptr = ((uint8_t*) c) + 1;
+		if (addr < c - mem + 1) {
+			return (struct segment) {
+				.start = start,
+				.end = end + 1,
+				.description = "Original filename",
+			};
+		}
+	}
+
+	if (header->flg & FCOMMENT) {
+		void *c = memchr(ptr, '\0', (ptr - mem) + len);
+		ptr = ((uint8_t*) c) + 1;
+		if (addr < c - mem + 1) {
+			size_t start = ptr - mem;
+			size_t end = c - mem;
+			return (struct segment) {
+				.start = start,
+				.end = end + 1,
+				.description = "File comment",
+			};
+		}
+	}
+
+	if (header->flg & FHCRC) {
+		if (addr < ptr - mem + 2) {
+			buf = malloc(1000);
+			fprintf(buf, "CRC16=" PRIu16, *((uint16_t*) ptr));
+			return (struct segment) {
+				.start = ptr - mem,
+				.end = ptr - mem + 2,
+				.description = buf,
+			};
+		}
+		ptr = (uint16_t*) ptr + 1;
+	}
+
+	if (len - addr < 4) {
+		buf = malloc(1000);
+		fprintf(buf, "ISIZE" PRIu32, *(((uint32_t*) ((uint8_t*) (mem + len))) - 1));
+		return (struct segment) {
+			.start = len - 4,
+			.end = len,
+			.description = buf,
+		};
+	}
+
+	if (len - addr - 4 < 4) {
+		buf = malloc(1000);
+		fprintf(buf, "CRC32" PRIu32, *(((uint32_t*) ((uint8_t*) (mem + len))) - 2));
+		return (struct segment) {
+			.start = len - 8,
+			.end = len - 4,
+			.description = buf,
+		};
+	}
+
+	if (ptr - mem <= addr && addr < ptr - mem + len - 8) {
+		return (struct segment) {
+			.start = ptr - mem,
+				.end = len - 8,
+				.description = "ZLIB compressed payload",
+		};
+	}
+
+
+	return empty_segment;
+
+}