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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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C
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#include <linux/bootconfig.h>
#define pr_err(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
/* Bootconfig footer is [size][csum][BOOTCONFIG_MAGIC]. */#define BOOTCONFIG_FOOTER_SIZE \ (sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN)
static int xbc_show_value(struct xbc_node *node, bool semicolon){ const char *val, *eol; char q; int i = 0;
eol = semicolon ? ";\n" : "\n"; xbc_array_for_each_value(node, val) { if (strchr(val, '"')) q = '\''; else q = '"'; printf("%c%s%c%s", q, val, q, xbc_node_is_array(node) ? ", " : eol); i++; } return i;}
static void xbc_show_compact_tree(void){ struct xbc_node *node, *cnode = NULL, *vnode; int depth = 0, i;
node = xbc_root_node(); while (node && xbc_node_is_key(node)) { for (i = 0; i < depth; i++) printf("\t"); if (!cnode) cnode = xbc_node_get_child(node); while (cnode && xbc_node_is_key(cnode) && !cnode->next) { vnode = xbc_node_get_child(cnode); /* * If @cnode has value and subkeys, this * should show it as below. * * key(@node) { * key(@cnode) = value; * key(@cnode) { * subkeys; * } * } */ if (vnode && xbc_node_is_value(vnode) && vnode->next) break; printf("%s.", xbc_node_get_data(node)); node = cnode; cnode = vnode; } if (cnode && xbc_node_is_key(cnode)) { printf("%s {\n", xbc_node_get_data(node)); depth++; node = cnode; cnode = NULL; continue; } else if (cnode && xbc_node_is_value(cnode)) { printf("%s = ", xbc_node_get_data(node)); xbc_show_value(cnode, true); /* * If @node has value and subkeys, continue * looping on subkeys with same node. */ if (cnode->next) { cnode = xbc_node_get_next(cnode); continue; } } else { printf("%s;\n", xbc_node_get_data(node)); } cnode = NULL;
if (node->next) { node = xbc_node_get_next(node); continue; } while (!node->next) { node = xbc_node_get_parent(node); if (!node) return; if (!xbc_node_get_child(node)->next) continue; if (depth) { depth--; for (i = 0; i < depth; i++) printf("\t"); printf("}\n"); } } node = xbc_node_get_next(node); }}
static void xbc_show_list(void){ char key[XBC_KEYLEN_MAX]; struct xbc_node *leaf; const char *val; int ret;
xbc_for_each_key_value(leaf, val) { ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX); if (ret < 0) { fprintf(stderr, "Failed to compose key %d\n", ret); break; } printf("%s = ", key); if (!val || val[0] == '\0') { printf("\"\"\n"); continue; } xbc_show_value(xbc_node_get_child(leaf), false); }}
#define PAGE_SIZE 4096
static int load_xbc_fd(int fd, char **buf, int size){ int ret;
*buf = malloc(size + 1); if (!*buf) return -ENOMEM;
ret = read(fd, *buf, size); if (ret < 0) return -errno; (*buf)[size] = '\0';
return ret;}
/* Return the read size or -errno */static int load_xbc_file(const char *path, char **buf){ struct stat stat; int fd, ret;
fd = open(path, O_RDONLY); if (fd < 0) return -errno; ret = fstat(fd, &stat); if (ret < 0) { ret = -errno; close(fd); return ret; }
ret = load_xbc_fd(fd, buf, stat.st_size);
close(fd);
return ret;}
static int pr_errno(const char *msg, int err){ pr_err("%s: %d\n", msg, err); return err;}
static int load_xbc_from_initrd(int fd, char **buf){ struct stat stat; int ret; uint32_t size = 0, csum = 0, rcsum; char magic[BOOTCONFIG_MAGIC_LEN]; const char *msg;
ret = fstat(fd, &stat); if (ret < 0) return -errno;
if (stat.st_size < BOOTCONFIG_FOOTER_SIZE) return 0;
if (lseek(fd, -(off_t)BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) return pr_errno("Failed to lseek for magic", -errno);
if (read(fd, magic, BOOTCONFIG_MAGIC_LEN) < 0) return pr_errno("Failed to read", -errno);
/* Check the bootconfig magic bytes */ if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0) return 0;
if (lseek(fd, -(off_t)BOOTCONFIG_FOOTER_SIZE, SEEK_END) < 0) return pr_errno("Failed to lseek for size", -errno);
if (read(fd, &size, sizeof(uint32_t)) < 0) return pr_errno("Failed to read size", -errno); size = le32toh(size);
if (read(fd, &csum, sizeof(uint32_t)) < 0) return pr_errno("Failed to read checksum", -errno); csum = le32toh(csum);
/* Wrong size error */ if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) { pr_err("bootconfig size is too big\n"); return -E2BIG; }
if (lseek(fd, stat.st_size - (size + BOOTCONFIG_FOOTER_SIZE), SEEK_SET) < 0) return pr_errno("Failed to lseek", -errno);
ret = load_xbc_fd(fd, buf, size); if (ret < 0) return ret;
/* Wrong Checksum */ rcsum = xbc_calc_checksum(*buf, size); if (csum != rcsum) { pr_err("checksum error: %u != %u\n", csum, rcsum); return -EINVAL; }
ret = xbc_init(*buf, size, &msg, NULL); /* Wrong data */ if (ret < 0) { pr_err("parse error: %s.\n", msg); return ret; }
return size;}
static void show_xbc_error(const char *data, const char *msg, int pos){ int lin = 1, col, i;
if (pos < 0) { pr_err("Error: %s.\n", msg); return; }
/* Note that pos starts from 0 but lin and col should start from 1. */ col = pos + 1; for (i = 0; i < pos; i++) { if (data[i] == '\n') { lin++; col = pos - i; } } pr_err("Parse Error: %s at %d:%d\n", msg, lin, col);
}
static int init_xbc_with_error(char *buf, int len){ char *copy = strdup(buf); const char *msg; int ret, pos;
if (!copy) return -ENOMEM;
ret = xbc_init(buf, len, &msg, &pos); if (ret < 0) show_xbc_error(copy, msg, pos); free(copy);
return ret;}
static int show_xbc_kernel_cmdline(void){ struct xbc_node *root; char *buf = NULL; int len, ret;
root = xbc_find_node("kernel"); if (!root) return 0; /* no kernel.* keys: emit empty output */
len = xbc_snprint_cmdline(NULL, 0, root); if (len < 0) { pr_err("Failed to size cmdline output: %d\n", len); return len; } if (len == 0) return 0;
buf = malloc(len + 1); if (!buf) return -ENOMEM;
ret = xbc_snprint_cmdline(buf, len + 1, root); if (ret < 0) { pr_err("Failed to render cmdline output: %d\n", ret); free(buf); return ret; }
fputs(buf, stdout); free(buf); return 0;}
static int show_xbc(const char *path, bool list, bool render_cmdline){ int ret, fd; char *buf = NULL; struct stat st;
ret = stat(path, &st); if (ret < 0) { ret = -errno; pr_err("Failed to stat %s: %d\n", path, ret); return ret; }
fd = open(path, O_RDONLY); if (fd < 0) { ret = -errno; pr_err("Failed to open initrd %s: %d\n", path, ret); return ret; }
ret = load_xbc_from_initrd(fd, &buf); close(fd); if (ret < 0) { pr_err("Failed to load a boot config from initrd: %d\n", ret); goto out; } /* Assume a bootconfig file if it is enough small */ if (ret == 0 && st.st_size <= XBC_DATA_MAX) { ret = load_xbc_file(path, &buf); if (ret < 0) { pr_err("Failed to load a boot config: %d\n", ret); goto out; } if (init_xbc_with_error(buf, ret) < 0) goto out; } if (render_cmdline) ret = show_xbc_kernel_cmdline(); else if (list) xbc_show_list(); else xbc_show_compact_tree(); if (ret > 0) ret = 0;out: free(buf);
return ret;}
static int delete_xbc(const char *path){ struct stat stat; int ret = 0, fd, size; char *buf = NULL;
fd = open(path, O_RDWR); if (fd < 0) { ret = -errno; pr_err("Failed to open initrd %s: %d\n", path, ret); return ret; }
size = load_xbc_from_initrd(fd, &buf); if (size < 0) { ret = size; pr_err("Failed to load a boot config from initrd: %d\n", ret); } else if (size > 0) { ret = fstat(fd, &stat); if (!ret) ret = ftruncate(fd, stat.st_size - size - BOOTCONFIG_FOOTER_SIZE); if (ret) ret = -errno; } /* Ignore if there is no boot config in initrd */
close(fd); free(buf);
return ret;}
static int apply_xbc(const char *path, const char *xbc_path){ struct { uint32_t size; uint32_t csum; char magic[BOOTCONFIG_MAGIC_LEN]; } footer; char *buf, *data; size_t total_size; struct stat stat; const char *msg; uint32_t size, csum; int pos, pad; int ret, fd;
ret = load_xbc_file(xbc_path, &buf); if (ret < 0) { pr_err("Failed to load %s : %d\n", xbc_path, ret); return ret; } size = strlen(buf) + 1; csum = xbc_calc_checksum(buf, size);
/* Backup the bootconfig data */ data = calloc(size + BOOTCONFIG_ALIGN + BOOTCONFIG_FOOTER_SIZE, 1); if (!data) { free(buf); return -ENOMEM; } memcpy(data, buf, size);
/* Check the data format */ ret = xbc_init(buf, size, &msg, &pos); if (ret < 0) { show_xbc_error(data, msg, pos); free(data); free(buf);
return ret; } printf("Apply %s to %s\n", xbc_path, path); xbc_get_info(&ret, NULL); printf("\tNumber of nodes: %d\n", ret); printf("\tSize: %u bytes\n", (unsigned int)size); printf("\tChecksum: %u\n", (unsigned int)csum);
/* TODO: Check the options by schema */ xbc_exit(); free(buf);
/* Remove old boot config if exists */ ret = delete_xbc(path); if (ret < 0) { pr_err("Failed to delete previous boot config: %d\n", ret); free(data); return ret; }
/* Apply new one */ fd = open(path, O_RDWR | O_APPEND); if (fd < 0) { ret = -errno; pr_err("Failed to open %s: %d\n", path, ret); free(data); return ret; } /* TODO: Ensure the @path is initramfs/initrd image */ if (fstat(fd, &stat) < 0) { ret = -errno; pr_err("Failed to get the size of %s\n", path); goto out; }
/* To align up the total size to BOOTCONFIG_ALIGN, get padding size */ total_size = stat.st_size + size + BOOTCONFIG_FOOTER_SIZE; pad = ((total_size + BOOTCONFIG_ALIGN - 1) & (~BOOTCONFIG_ALIGN_MASK)) - total_size; size += pad;
/* Add a footer */ footer.size = htole32(size); footer.csum = htole32(csum); memcpy(footer.magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN); static_assert(sizeof(footer) == BOOTCONFIG_FOOTER_SIZE); memcpy(data + size, &footer, BOOTCONFIG_FOOTER_SIZE);
total_size = size + BOOTCONFIG_FOOTER_SIZE;
ret = write(fd, data, total_size); if (ret < total_size) { if (ret < 0) ret = -errno; pr_err("Failed to apply a boot config: %d\n", ret); if (ret >= 0) goto out_rollback; } else ret = 0;
out: close(fd); free(data);
return ret;
out_rollback: /* Map the partial write to -ENOSPC */ if (ret >= 0) ret = -ENOSPC; if (ftruncate(fd, stat.st_size) < 0) { ret = -errno; pr_err("Failed to rollback the write error: %d\n", ret); pr_err("The initrd %s may be corrupted. Recommend to rebuild.\n", path); } goto out;}
static int usage(void){ printf("Usage: bootconfig [OPTIONS] <INITRD>\n" "Or bootconfig <CONFIG>\n" " Apply, delete or show boot config to initrd.\n" " Options:\n" " -a <config>: Apply boot config to initrd\n" " -d : Delete boot config file from initrd\n" " -l : list boot config in initrd or file\n" " -C : render the kernel.* subtree as a flat cmdline\n" " string (suitable for embedding in a kernel image)\n" " and print it to stdout\n\n" " If no option is given, show the bootconfig in the given file.\n"); return -1;}
int main(int argc, char **argv){ char *path = NULL; char *apply = NULL; bool render_cmdline = false; bool delete = false, list = false; int opt;
while ((opt = getopt(argc, argv, "hda:lC")) != -1) { switch (opt) { case 'd': delete = true; break; case 'a': apply = optarg; break; case 'l': list = true; break; case 'C': render_cmdline = true; break; case 'h': default: return usage(); } }
if ((!!apply + !!delete + !!list + !!render_cmdline) > 1) { pr_err("Error: You can give one of -a, -d, -l or -C at once.\n"); return usage(); }
if (optind >= argc) { pr_err("Error: No initrd is specified.\n"); return usage(); }
path = argv[optind];
if (apply) return apply_xbc(path, apply); else if (delete) return delete_xbc(path);
return show_xbc(path, list, render_cmdline);}