Add function "KernAux_Multiboot2_boot_cmd_line"

.gitignore

@@ -26,5 +26,6 @@
 
 /tests/multiboot2_print1
 /tests/multiboot2_print2
+/tests/test_multiboot2_helpers
 /tests/test_multiboot2_print
 /tests/test_multiboot2_validation

Makefile.am

@@ -5,6 +5,7 @@ AM_CFLAGS = -std=c99 -Wall -Wextra -I$(top_srcdir)/include
 lib_LIBRARIES = libkernaux.a
 
 TESTS = \
+	tests/test_multiboot2_helpers \
 	tests/test_multiboot2_print \
 	tests/test_multiboot2_validation
 
@@ -15,6 +16,7 @@ noinst_PROGRAMS = \
 
 libkernaux_a_SOURCES = \
 	src/arch/i386.S \
+	src/multiboot2/helpers.c \
 	src/multiboot2/is_valid.c \
 	src/multiboot2/print.c \
 	src/pfa.c
@@ -27,6 +29,10 @@ tests_multiboot2_print2_SOURCES = \
 	$(libkernaux_a_SOURCES) \
 	tests/multiboot2_print2.c
 
+tests_test_multiboot2_helpers_SOURCES = \
+	$(libkernaux_a_SOURCES) \
+	tests/test_multiboot2_helpers.c
+
 tests_test_multiboot2_print_SOURCES = \
 	$(libkernaux_a_SOURCES) \
 	tests/test_multiboot2_print.c

include/kernaux/multiboot2.h

@@ -304,6 +304,15 @@ struct KernAux_Multiboot2_Tag_MemoryMap_EntryBase {
 }
 __attribute__((packed));
 
+/********************
+ * Helper functions *
+ ********************/
+
+const char *KernAux_Multiboot2_boot_cmd_line(
+    const struct KernAux_Multiboot2 *multiboot2
+)
+__attribute__((nonnull));
+
 /*******************
  * Print functions *
  *******************/

src/multiboot2/helpers.c

@@ -0,0 +1,27 @@
+#include <kernaux/multiboot2.h>
+
+const char *KernAux_Multiboot2_boot_cmd_line(
+    const struct KernAux_Multiboot2 *const multiboot2
+) {
+    const struct KernAux_Multiboot2_TagBase *tag_base =
+        (struct KernAux_Multiboot2_TagBase*)multiboot2->data;
+
+    while ((void*)tag_base < (void*)multiboot2 + multiboot2->total_size) {
+        if (!KernAux_Multiboot2_TagBase_is_valid(tag_base)) {
+            return 0;
+        }
+
+        if (tag_base->type == KERNAUX_MULTIBOOT2_TAGTYPE_BOOT_CMD_LINE) {
+            const struct KernAux_Multiboot2_Tag_BootCmdLine *const tag =
+                (struct KernAux_Multiboot2_Tag_BootCmdLine*)tag_base;
+
+            return tag->cmdline;
+        }
+
+        tag_base = (struct KernAux_Multiboot2_TagBase*)(
+            (void*)tag_base + ((tag_base->size + 7) & ~7)
+        );
+    }
+
+    return 0;
+}

src/multiboot2/print.c

@@ -77,10 +77,6 @@ void KernAux_Multiboot2_print(
     print("  size: %u\n", multiboot2->total_size);
     print("  reserved1: %u\n", multiboot2->reserved1);
 
-    if (multiboot2->total_size <= 8) {
-        return;
-    }
-
     const struct KernAux_Multiboot2_TagBase *tag_base =
         (struct KernAux_Multiboot2_TagBase*)multiboot2->data;
 

tests/test_multiboot2_helpers.c

@@ -0,0 +1,142 @@
+#include <kernaux/multiboot2.h>
+
+#include <assert.h>
+
+static const struct {
+    struct KernAux_Multiboot2 multiboot2;
+    struct KernAux_Multiboot2_Tag_None tag_none;
+} multiboot2_without_boot_cmd_line = {
+    .multiboot2 = {
+        .total_size = sizeof(multiboot2_without_boot_cmd_line),
+        .reserved1 = 0,
+    },
+    .tag_none = {
+        .base = {
+            .type = KERNAUX_MULTIBOOT2_TAGTYPE_NONE,
+            .size = sizeof(multiboot2_without_boot_cmd_line.tag_none),
+        },
+    },
+};
+
+static const struct {
+    struct KernAux_Multiboot2 multiboot2;
+
+    struct {
+        struct KernAux_Multiboot2_Tag_BootCmdLine tag;
+        char cmdline[14];
+    } tag_boot_cmd_line;
+
+    unsigned char _align1[2];
+
+    struct KernAux_Multiboot2_Tag_None tag_none;
+} multiboot2_with_some_boot_cmd_line = {
+    .multiboot2 = {
+        .total_size = sizeof(multiboot2_with_some_boot_cmd_line),
+        .reserved1 = 0,
+    },
+    .tag_boot_cmd_line = {
+        .tag = {
+            .base = {
+                .type = KERNAUX_MULTIBOOT2_TAGTYPE_BOOT_CMD_LINE,
+                .size = sizeof(
+                    multiboot2_with_some_boot_cmd_line.tag_boot_cmd_line
+                ),
+            },
+        },
+        .cmdline = "Hello, World!\0",
+    },
+    .tag_none = {
+        .base = {
+            .type = KERNAUX_MULTIBOOT2_TAGTYPE_NONE,
+            .size = sizeof(multiboot2_with_some_boot_cmd_line.tag_none),
+        },
+    },
+};
+
+static const struct {
+    struct KernAux_Multiboot2 multiboot2;
+
+    struct {
+        struct KernAux_Multiboot2_Tag_BootCmdLine tag;
+        char cmdline[14];
+    } tag_boot_cmd_line1;
+
+    unsigned char _align1[2];
+
+    struct {
+        struct KernAux_Multiboot2_Tag_BootCmdLine tag;
+        char cmdline[13];
+    } tag_boot_cmd_line2;
+
+    unsigned char _align2[3];
+
+    struct KernAux_Multiboot2_Tag_None tag_none;
+} multiboot2_with_two_boot_cmd_lines = {
+    .multiboot2 = {
+        .total_size = sizeof(multiboot2_with_two_boot_cmd_lines),
+        .reserved1 = 0,
+    },
+    .tag_boot_cmd_line1 = {
+        .tag = {
+            .base = {
+                .type = KERNAUX_MULTIBOOT2_TAGTYPE_BOOT_CMD_LINE,
+                .size = sizeof(
+                    multiboot2_with_two_boot_cmd_lines.tag_boot_cmd_line1
+                ),
+            },
+        },
+        .cmdline = "Hello, World!\0",
+    },
+    .tag_boot_cmd_line2 = {
+        .tag = {
+            .base = {
+                .type = KERNAUX_MULTIBOOT2_TAGTYPE_BOOT_CMD_LINE,
+                .size = sizeof(
+                    multiboot2_with_two_boot_cmd_lines.tag_boot_cmd_line2
+                ),
+            },
+        },
+        .cmdline = "Hello again!\0",
+    },
+    .tag_none = {
+        .base = {
+            .type = KERNAUX_MULTIBOOT2_TAGTYPE_NONE,
+            .size = sizeof(multiboot2_with_two_boot_cmd_lines.tag_none),
+        },
+    },
+};
+
+int main()
+{
+    assert(KernAux_Multiboot2_is_valid(
+        &multiboot2_without_boot_cmd_line.multiboot2
+    ));
+
+    assert(KernAux_Multiboot2_is_valid(
+        &multiboot2_with_some_boot_cmd_line.multiboot2
+    ));
+
+    assert(KernAux_Multiboot2_is_valid(
+        &multiboot2_with_two_boot_cmd_lines.multiboot2
+    ));
+
+    assert(
+        KernAux_Multiboot2_boot_cmd_line(
+            &multiboot2_without_boot_cmd_line.multiboot2
+        ) == 0
+    );
+
+    assert(
+        KernAux_Multiboot2_boot_cmd_line(
+            &multiboot2_with_some_boot_cmd_line.multiboot2
+        ) == multiboot2_with_some_boot_cmd_line.tag_boot_cmd_line.cmdline
+    );
+
+    assert(
+        KernAux_Multiboot2_boot_cmd_line(
+            &multiboot2_with_two_boot_cmd_lines.multiboot2
+        ) == multiboot2_with_two_boot_cmd_lines.tag_boot_cmd_line1.cmdline
+    );
+
+    return 0;
+}