source: bootcd/isolinux/syslinux-6.03/com32/elflink/ldlinux/kernel.c

#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <console.h>
#include <dprintf.h>
#include <syslinux/loadfile.h>
#include <syslinux/linux.h>
#include <syslinux/pxe.h>
#include "core.h"

const char *globaldefault = NULL;
const char *append = NULL;

/* Will be called from readconfig.c */
int new_linux_kernel(char *okernel, char *ocmdline)
{
        const char *kernel_name = NULL, *args = NULL;
        struct initramfs *initramfs = NULL;
        char *temp;
        void *kernel_data;
        size_t kernel_len, cmdline_len;
        bool opt_quiet = false;
        char *initrd_name, *cmdline;

        dprintf("okernel = %s, ocmdline = %s", okernel, ocmdline);

        if (okernel)
                kernel_name = okernel;
        else if (globaldefault)
                kernel_name = globaldefault;

        if (ocmdline)
                args = ocmdline;
        else if (append)
                args = append;

        cmdline_len = strlen("BOOT_IMAGE=") + strlen(kernel_name);
        cmdline_len += 1;       /* space between BOOT_IMAGE and args */
        cmdline_len += strlen(args);
        cmdline_len += 1;       /* NUL-termination */

        cmdline = malloc(cmdline_len);
        if (!cmdline) {
            printf("Failed to alloc memory for cmdline\n");
            return 1;
        }

        sprintf(cmdline, "BOOT_IMAGE=%s %s", kernel_name, args);

        /* "keeppxe" handling */
#if IS_PXELINUX
        extern char KeepPXE;

        if (strstr(cmdline, "keeppxe"))
                KeepPXE |= 1;
#endif

        if (strstr(cmdline, "quiet"))
                opt_quiet = true;

        if (!opt_quiet)
                printf("Loading %s... ", kernel_name);

        if (loadfile(kernel_name, &kernel_data, &kernel_len)) {
                if (opt_quiet)
                        printf("Loading %s ", kernel_name);
                printf("failed: ");
                goto bail;
        }

        if (!opt_quiet)
                printf("ok\n");

        /* Find and load initramfs */
        temp = strstr(cmdline, "initrd=");
        if (temp) {
                /* Initialize the initramfs chain */
                initramfs = initramfs_init();
                if (!initramfs)
                        goto bail;

                temp += 6; /* strlen("initrd") */
                do {
                    size_t n = 0;
                    char *p;

                    temp++;     /* Skip = or , */

                    p = temp;
                    while (*p != ' ' && *p != ',' && *p) {
                        p++;
                        n++;
                    }

                    initrd_name = malloc(n + 1);
                    if (!initrd_name) {
                        printf("Failed to allocate space for initrd\n");
                        goto bail;
                    }

                    snprintf(initrd_name, n + 1, "%s", temp);
                    temp += n;

                    if (!opt_quiet)
                        printf("Loading %s...", initrd_name);

                    if (initramfs_load_archive(initramfs, initrd_name)) {
                        if (opt_quiet)
                            printf("Loading %s ", initrd_name);
                        free(initrd_name);
                        printf("failed: ");
                        goto bail;
                    }

                    free(initrd_name);

                    if (!opt_quiet)
                        printf("ok\n");
                } while (*temp == ',');
        }

        /* This should not return... */
        syslinux_boot_linux(kernel_data, kernel_len, initramfs, NULL, cmdline);
        printf("Booting kernel failed: ");

bail:
        free(cmdline);
        printf("%s\n", strerror(errno));
        return 1;
}