Just a bit of cleanup.

2 files changed, 56 insertions, 41 deletions

diff --git a/README.md b/README.md
index 8f8eabb..8bd3b71 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ if you have a full musl toolchain) followed by `make install` instead.
 - `--minimum-image-size <size>`
   minimum size of the image in sectors (defaults to 2048)
 - `--disk-guid <guid>`
-  GUID of the entire disk (see GUID format below - defaults to random)
+  GUID of the entire disk (see GUID format below, defaults to random)
 - `--part <file> <options>`
   begin a partition entry containing the specified image as its data and
   options as below
@@ -31,19 +31,19 @@ if you have a full musl toolchain) followed by `make install` instead.
 - `--name <name>`
   set the name of the entry in the GPT
 - `--type <type>`
-  set the type of the entry, either a GUID, MBR partition ID _in decimal_ or
-  one of the known paritition types
+  set the type of the entry, either a GUID, numeric MBR-style partition ID, or
+  one of the known partition types
 - `--uuid <guid>`
-  specify the UUID of the partition in the GPT (defaults to a random uuid)
+  specify the UUID of the partition in the GPT (defaults to a random UUID)
 
 ### Known partition types
 
-- `system` EFI sytem partition
-- `bios` BIOS boot partition
+- EFI system partition: `system`
+- BIOS boot partition: `bios`
 - FAT types: `fat12`, `fat16`, `fat16b`, `fat32`, `fat16x`, `fat32x`, `fat16+`,
   `fat32+`
 - NTFS types: `ntfs`
-- Linux types: `linux`
+- Linux types: `linux`, `swap`
 
 ### GUID format
 
diff --git a/part_ids.c b/part_ids.c
index d678598..84f4189 100644
--- a/part_ids.c
+++ b/part_ids.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: MIT */
+
 #include "part_ids.h"
 
 #include <ctype.h>
@@ -5,32 +7,27 @@
 #include <stdlib.h>
 #include <errno.h>
 
-#define MBR_SWAP 0x82
-#define MBR_LINUX 0x83
-#define EFI_SYSTEM 0x100
-#define BIOS_BOOT 0x101
-
 #define GUID_TABLE \
-	X(SWAP, "0657FD6D-A4AB-43C4-84E5-0933C84B4F4F") \
-	X(LINUX, "0FC63DAF-8483-4772-8E79-3D69D8477DE4") \
-	X(SYSTEM, "C12A7328-F81F-11D2-BA4B-00A0C93EC93B") \
-	X(BDP, "EBD0A0A2-B9E5-4433-87C0-68B6B72699C7") \
-	X(BIOS, "21686148-6449-6E6F-744E-656564454649")
+	X(LINUX_SWAP, "0657FD6D-A4AB-43C4-84E5-0933C84B4F4F") \
+	X(LINUX_FS, "0FC63DAF-8483-4772-8E79-3D69D8477DE4") \
+	X(EFI_SYSTEM, "C12A7328-F81F-11D2-BA4B-00A0C93EC93B") \
+	X(MS_BASIC_DATA, "EBD0A0A2-B9E5-4433-87C0-68B6B72699C7") \
+	X(BIOS_BOOT, "21686148-6449-6E6F-744E-656564454649")
 
 #define ALIAS_TABLE \
-	X("fat12", 0x01, BDP) \
-	X("fat16", 0x04, BDP) \
-	X("fat16b", 0x06, BDP) \
-	X("ntfs", 0x07, BDP) \
-	X("fat32", 0x0b, BDP) \
-	X("fat32x", 0x0c, BDP) \
-	X("fat16x", 0x0e, BDP) \
-	X("fat16+", 0x28, BDP) \
-	X("fat32+", 0x29, BDP) \
-	X("swap", MBR_SWAP, SWAP) \
-	X("linux", MBR_LINUX, LINUX) \
-	X("system", EFI_SYSTEM, SYSTEM) \
-	X("bios", BIOS_BOOT, BIOS)
+	X("fat12", 0x01, MS_BASIC_DATA) \
+	X("fat16", 0x04, MS_BASIC_DATA) \
+	X("fat16b", 0x06, MS_BASIC_DATA) \
+	X("ntfs", 0x07, MS_BASIC_DATA) \
+	X("fat32", 0x0b, MS_BASIC_DATA) \
+	X("fat32x", 0x0c, MS_BASIC_DATA) \
+	X("fat16x", 0x0e, MS_BASIC_DATA) \
+	X("fat16+", 0x28, MS_BASIC_DATA) \
+	X("fat32+", 0x29, MS_BASIC_DATA) \
+	X("swap", 0x82, LINUX_SWAP) \
+	X("linux", 0x83, LINUX_FS) \
+	X("system", 0x100, EFI_SYSTEM) \
+	X("bios", 0x101, BIOS_BOOT)
 
 /* First we generate compact indices for each GUID using an enum. */
 enum GUID_INDEX {
@@ -45,7 +42,7 @@ enum GUID_INDEX {
  * that there are no pointers involved and no NUL terminators at the "end" of
  * a GUID, so don't try to `printf` them directly!
  */
-static char guids[NUM_GUIDS][GUID_STRLEN] = {
+static const char guids[NUM_GUIDS][GUID_STRLEN] = {
 #define X(index, guid) [GUID_ ## index] = guid,
 	GUID_TABLE
 #undef X
@@ -56,7 +53,7 @@ static char guids[NUM_GUIDS][GUID_STRLEN] = {
  * sorted, but unless we have thousands of names, a linear search should be
  * all we need. A `key` of `NULL` marks the end.
  */
-static struct {char *key; int value;} name_to_guid[] = {
+static const struct {char *key; int value;} name_to_guid[] = {
 #define X(name, id, index) {name, GUID_ ## index},
 	ALIAS_TABLE
 #undef X
@@ -66,7 +63,7 @@ static struct {char *key; int value;} name_to_guid[] = {
 /*
  * The same for the "short" MBR-style ids. A `key` of `-1` marks the end.
  */
-static struct {int key; int value;} mbr_to_guid[] = {
+static const struct {int key; int value;} mbr_to_guid[] = {
 #define X(name, id, index) {id, GUID_ ## index},
 	ALIAS_TABLE
 #undef X
@@ -106,6 +103,28 @@ valid_string_guid(const char str[GUID_STRLEN])
 	return 1;
 }
 
+static int
+find_by_name(const char *str, GUID *guid)
+{
+	for (int i = 0; name_to_guid[i].key != NULL; i++) {
+		if (!strcmp(str, name_to_guid[i].key)) {
+			return string_to_guid(guid, guids[name_to_guid[i].value]);
+		}
+	}
+	return -1;
+}
+
+static int
+find_by_id(const int id, GUID *guid)
+{
+	for (int i = 0; mbr_to_guid[i].key != -1; i++) {
+		if (mbr_to_guid[i].key == id) {
+			return string_to_guid(guid, guids[mbr_to_guid[i].value]);
+		}
+	}
+	return -1;
+}
+
 /*
  * Parse GUID/UUID notation used on the command line.
  * Returns 0 on success.
@@ -119,10 +138,8 @@ parse_guid(const char *str, GUID *guid)
 	}
 
 	/* detect by name */
-	for (int i = 0; name_to_guid[i].key != NULL; i++) {
-		if (!strcmp(str, name_to_guid[i].key)) {
-			return string_to_guid(guid, guids[name_to_guid[i].value]);
-		}
+	if (find_by_name(str, guid) == 0) {
+		return 0;
 	}
 
 	/* try and parse as guid */
@@ -136,10 +153,8 @@ parse_guid(const char *str, GUID *guid)
 	if (errno != 0) {
 		return -1;
 	}
-	for (int i = 0; mbr_to_guid[i].key != -1; i++) {
-		if (mbr_to_guid[i].key == mbr_id) {
-			return string_to_guid(guid, guids[mbr_to_guid[i].value]);
-		}
+	if (find_by_id(mbr_id, guid) == 0) {
+		return 0;
 	}
 
 	return -1;