[syslinux:master] chain.c: move file mangling outside main()
syslinux-bot for Michal Soltys
soltys at ziu.info
Mon Mar 26 15:03:07 PDT 2012
Commit-ID: 2905564db097f2fbf5f5fb28fdc059f2eaa9378e
Gitweb: http://www.syslinux.org/commit/2905564db097f2fbf5f5fb28fdc059f2eaa9378e
Author: Michal Soltys <soltys at ziu.info>
AuthorDate: Sun, 15 Aug 2010 23:00:59 +0200
Committer: Michal Soltys <soltys at ziu.info>
CommitDate: Mon, 16 Aug 2010 00:41:45 +0200
chain.c: move file mangling outside main()
All the file mangling code has been moved to
mangle_*() family of functions, currently:
mangle_isolinux()
mangle_grublegacy()
mangle_grldr()
mangle_drmk()
They will be further moved to separate file.
Also, file and sector loading routines are now near each other.
Signed-off-by: Michal Soltys <soltys at ziu.info>
---
com32/chain/chain.c | 494 +++++++++++++++++++++++++++------------------------
1 files changed, 263 insertions(+), 231 deletions(-)
diff --git a/com32/chain/chain.c b/com32/chain/chain.c
index 6fcdf03..c7f7521 100644
--- a/com32/chain/chain.c
+++ b/com32/chain/chain.c
@@ -673,6 +673,223 @@ bail:
return -1;
}
+/* Create boot info table: needed when you want to chainload
+ * another version of ISOLINUX (or another bootlaoder that needs
+ * the -boot-info-table switch of mkisofs)
+ * (will only work when run from ISOLINUX)
+ */
+static int mangle_isolinux(struct data_area *_data)
+{
+ const union syslinux_derivative_info *sdi;
+ unsigned char *isolinux_bin;
+ uint32_t *checksum, *chkhead, *chktail;
+ uint32_t file_lba = 0;
+
+ sdi = syslinux_derivative_info();
+
+ if (sdi->c.filesystem != SYSLINUX_FS_ISOLINUX) {
+ error ("The isolinux= option is only valid when run from ISOLINUX.\n");
+ goto bail;
+ }
+
+ /* Boot info table info (integers in little endian format)
+
+ Offset Name Size Meaning
+ 8 bi_pvd 4 bytes LBA of primary volume descriptor
+ 12 bi_file 4 bytes LBA of boot file
+ 16 bi_length 4 bytes Boot file length in bytes
+ 20 bi_csum 4 bytes 32-bit checksum
+ 24 bi_reserved 40 bytes Reserved
+
+ The 32-bit checksum is the sum of all the 32-bit words in the
+ boot file starting at byte offset 64. All linear block
+ addresses (LBAs) are given in CD sectors (normally 2048 bytes).
+
+ LBA of primary volume descriptor should already be set to 16.
+ */
+
+ isolinux_bin = (unsigned char *)_data->data;
+
+ /* Get LBA address of bootfile */
+ file_lba = get_file_lba(opt.loadfile);
+
+ if (file_lba == 0) {
+ error("Failed to find LBA offset of the boot file\n");
+ goto bail;
+ }
+ /* Set it */
+ *((uint32_t *) & isolinux_bin[12]) = file_lba;
+
+ /* Set boot file length */
+ *((uint32_t *) & isolinux_bin[16]) = _data->size;
+
+ /* Calculate checksum */
+ checksum = (uint32_t *) & isolinux_bin[20];
+ chkhead = (uint32_t *) & isolinux_bin[64];
+ chktail = (uint32_t *) & isolinux_bin[_data->size & ~3];
+ *checksum = 0;
+ while (chkhead < chktail)
+ *checksum += *chkhead++;
+
+ /*
+ * Deal with possible fractional dword at the end;
+ * this *should* never happen...
+ */
+ if (_data->size & 3) {
+ uint32_t xword = 0;
+ memcpy(&xword, chkhead, _data->size & 3);
+ *checksum += xword;
+ }
+ return 0;
+bail:
+ return -1;
+}
+
+/*
+ * GRLDR of GRUB4DOS wants the partition number in DH:
+ * -1: whole drive (default)
+ * 0-3: primary partitions
+ * 4-*: logical partitions
+ */
+static int mangle_grldr(const struct part_iter *_iter, struct syslinux_rm_regs *_regs)
+{
+ _regs->edx.b[1] = _iter->index - 1;
+ return 0;
+}
+
+/*
+ * Legacy grub's stage2 chainloading
+ */
+static int mangle_grublegacy(const struct part_iter *_iter, struct data_area *_data, struct syslinux_rm_regs *_regs)
+{
+ /* Layout of stage2 file (from byte 0x0 to 0x270) */
+ struct grub_stage2_patch_area {
+ /* 0x0 to 0x205 */
+ char unknown[0x206];
+ /* 0x206: compatibility version number major */
+ uint8_t compat_version_major;
+ /* 0x207: compatibility version number minor */
+ uint8_t compat_version_minor;
+
+ /* 0x208: install_partition variable */
+ struct {
+ /* 0x208: sub-partition in sub-partition part2 */
+ uint8_t part3;
+ /* 0x209: sub-partition in top-level partition */
+ uint8_t part2;
+ /* 0x20a: top-level partiton number */
+ uint8_t part1;
+ /* 0x20b: BIOS drive number (must be 0) */
+ uint8_t drive;
+ } __attribute__ ((packed)) install_partition;
+
+ /* 0x20c: deprecated (historical reason only) */
+ uint32_t saved_entryno;
+ /* 0x210: stage2_ID: will always be STAGE2_ID_STAGE2 = 0 in stage2 */
+ uint8_t stage2_id;
+ /* 0x211: force LBA */
+ uint8_t force_lba;
+ /* 0x212: version string (will probably be 0.97) */
+ char version_string[5];
+ /* 0x217: config filename */
+ char config_file[89];
+ /* 0x270: start of code (after jump from 0x200) */
+ char codestart[1];
+ } __attribute__ ((packed)) *stage2;
+
+ if (_data->size < sizeof(struct grub_stage2_patch_area)) {
+ error("The file specified by grub=<loader> is too small to be stage2 of GRUB Legacy.\n");
+ goto bail;
+ }
+ stage2 = _data->data;
+
+ /*
+ * Check the compatibility version number to see if we loaded a real
+ * stage2 file or a stage2 file that we support.
+ */
+ if (stage2->compat_version_major != 3
+ || stage2->compat_version_minor != 2) {
+ error("The file specified by grub=<loader> is not a supported stage2 GRUB Legacy binary.\n");
+ goto bail;
+ }
+
+ /* jump 0x200 bytes into the loadfile */
+ _regs->ip = 0x200;
+
+ /*
+ * GRUB Legacy wants the partition number in the install_partition
+ * variable, located at offset 0x208 of stage2.
+ * When GRUB Legacy is loaded, it is located at memory address 0x8208.
+ *
+ * It looks very similar to the "boot information format" of the
+ * Multiboot specification:
+ * http://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Boot-information-format
+ *
+ * 0x208 = part3: sub-partition in sub-partition part2
+ * 0x209 = part2: sub-partition in top-level partition
+ * 0x20a = part1: top-level partition number
+ * 0x20b = drive: BIOS drive number (must be 0)
+ *
+ * GRUB Legacy doesn't store the BIOS drive number at 0x20b, but at
+ * another location.
+ *
+ * Partition numbers always start from zero.
+ * Unused partition bytes must be set to 0xFF.
+ *
+ * We only care about top-level partition, so we only need to change
+ * "part1" to the appropriate value:
+ * -1: whole drive (default) (-1 = 0xFF)
+ * 0-3: primary partitions
+ * 4-*: logical partitions
+ */
+ stage2->install_partition.part1 = _iter->index - 1;
+
+ /*
+ * Grub Legacy reserves 89 bytes (from 0x8217 to 0x826f) for the
+ * config filename. The filename passed via grubcfg= will overwrite
+ * the default config filename "/boot/grub/menu.lst".
+ */
+ if (opt.grubcfg) {
+ if (strlen(opt.grubcfg) > sizeof(stage2->config_file) - 1) {
+ error ("The config filename length can't exceed 88 characters.\n");
+ goto bail;
+ }
+
+ strcpy((char *)stage2->config_file, opt.grubcfg);
+ }
+
+ return 0;
+bail:
+ return -1;
+}
+
+/*
+ * Dell's DRMK chainloading.
+ */
+static int mangle_drmk(struct data_area *_data, struct syslinux_rm_regs *_regs)
+{
+ /*
+ * DRMK entry is different than MS-DOS/PC-DOS
+ * A new size, aligned to 16 bytes to ease use of ds:[bp+28].
+ * We only really need 4 new, usable bytes at the end.
+ */
+
+ int tsize = (_data->size + 19) & 0xfffffff0;
+ _regs->ss = _regs->fs = _regs->gs = 0; /* Used before initialized */
+ if (!realloc(_data->data, tsize)) {
+ error("Failed to realloc for DRMK.\n");
+ goto bail;
+ }
+ _data->size = tsize;
+ /* ds:[bp+28] must be 0x0000003f */
+ _regs->ds = (tsize >> 4) + (opt.seg - 2);
+ /* "Patch" into tail of the new space */
+ *(int *)(_data->data + tsize - 4) = 0x0000003f;
+
+ return 0;
+bail:
+ return -1;
+}
int main(int argc, char *argv[])
{
@@ -684,7 +901,7 @@ int main(int argc, char *argv[])
struct syslinux_rm_regs regs;
struct data_area data[3];
- int ndata = 0;
+ int ndata = 0, fidx = -1, sidx = -1;
addr_t load_base;
openconsole(&dev_null_r, &dev_stdcon_w);
@@ -707,268 +924,83 @@ int main(int argc, char *argv[])
}
/* Get disk/part iterator matching user supplied options */
-
if(find_dp(&cur_part))
goto bail;
/* DOS kernels want the drive number in BL instead of DL. Indulge them. */
regs.ebx.b[0] = regs.edx.b[0] = cur_part->di.disk;
+ /* Do hide / unhide if appropriate */
if (opt.hide)
hide_unhide(cur_part);
- /* Do the actual chainloading */
+ /* Load file and bs/mbr */
+
load_base = opt.seg ? (opt.seg << 4) : 0x7c00;
if (opt.loadfile) {
fputs("Loading the boot file...\n", stdout);
if (loadfile(opt.loadfile, &data[ndata].data, &data[ndata].size)) {
- error("Failed to load the boot file.\n");
+ error("Couldn't read the boot file.\n");
goto bail;
}
- data[ndata].base = load_base;
file_area = (void *)data[ndata].data;
+ data[ndata].base = load_base;
load_base = 0x7c00; /* If we also load a boot sector */
+ fidx = ndata;
+ ndata++;
+ }
- /* Create boot info table: needed when you want to chainload
- another version of ISOLINUX (or another bootlaoder that needs
- the -boot-info-table switch of mkisofs)
- (will only work when run from ISOLINUX) */
- if (opt.isolinux) {
- const union syslinux_derivative_info *sdi;
- sdi = syslinux_derivative_info();
-
- if (sdi->c.filesystem == SYSLINUX_FS_ISOLINUX) {
- unsigned char *isolinux_bin;
- uint32_t *checksum, *chkhead, *chktail;
- uint32_t file_lba = 0;
- /* Boot info table info (integers in little endian format)
-
- Offset Name Size Meaning
- 8 bi_pvd 4 bytes LBA of primary volume descriptor
- 12 bi_file 4 bytes LBA of boot file
- 16 bi_length 4 bytes Boot file length in bytes
- 20 bi_csum 4 bytes 32-bit checksum
- 24 bi_reserved 40 bytes Reserved
-
- The 32-bit checksum is the sum of all the 32-bit words in the
- boot file starting at byte offset 64. All linear block
- addresses (LBAs) are given in CD sectors (normally 2048 bytes).
-
- LBA of primary volume descriptor should already be set to 16.
- */
-
- isolinux_bin = (unsigned char *)data[ndata].data;
-
- /* Get LBA address of bootfile */
- file_lba = get_file_lba(opt.loadfile);
-
- if (file_lba == 0) {
- error("Failed to find LBA offset of the boot file\n");
- goto bail;
- }
- /* Set it */
- *((uint32_t *) & isolinux_bin[12]) = file_lba;
-
- /* Set boot file length */
- *((uint32_t *) & isolinux_bin[16]) = data[ndata].size;
-
- /* Calculate checksum */
- checksum = (uint32_t *) & isolinux_bin[20];
- chkhead = (uint32_t *) & isolinux_bin[64];
- chktail = (uint32_t *) & isolinux_bin[data[ndata].size & ~3];
- *checksum = 0;
- while (chkhead < chktail)
- *checksum += *chkhead++;
-
- /*
- * Deal with possible fractional dword at the end;
- * this *should* never happen...
- */
- if (data[ndata].size & 3) {
- uint32_t xword = 0;
- memcpy(&xword, chkhead, data[ndata].size & 3);
- *checksum += xword;
- }
- } else {
- error
- ("The isolinux= option is only valid when run from ISOLINUX\n");
- goto bail;
- }
+ if (!opt.loadfile || data[0].base >= 0x7c00 + SECTOR) {
+ if (!(data[ndata].data = disk_read_sectors(&cur_part->di, cur_part->start_lba, 1))) {
+ error("Couldn't read the boot sector or mbr.\n");
+ goto bail;
}
- /*
- * GRLDR of GRUB4DOS wants the partition number in DH:
- * -1: whole drive (default)
- * 0-3: primary partitions
- * 4-*: logical partitions
- */
- if (opt.grldr)
- regs.edx.b[1] = cur_part->index - 1;
-
- /*
- * Legacy grub's stage2 chainloading
- */
- if (opt.grub) {
- /* Layout of stage2 file (from byte 0x0 to 0x270) */
- struct grub_stage2_patch_area {
- /* 0x0 to 0x205 */
- char unknown[0x206];
- /* 0x206: compatibility version number major */
- uint8_t compat_version_major;
- /* 0x207: compatibility version number minor */
- uint8_t compat_version_minor;
-
- /* 0x208: install_partition variable */
- struct {
- /* 0x208: sub-partition in sub-partition part2 */
- uint8_t part3;
- /* 0x209: sub-partition in top-level partition */
- uint8_t part2;
- /* 0x20a: top-level partiton number */
- uint8_t part1;
- /* 0x20b: BIOS drive number (must be 0) */
- uint8_t drive;
- } __attribute__ ((packed)) install_partition;
-
- /* 0x20c: deprecated (historical reason only) */
- uint32_t saved_entryno;
- /* 0x210: stage2_ID: will always be STAGE2_ID_STAGE2 = 0 in stage2 */
- uint8_t stage2_id;
- /* 0x211: force LBA */
- uint8_t force_lba;
- /* 0x212: version string (will probably be 0.97) */
- char version_string[5];
- /* 0x217: config filename */
- char config_file[89];
- /* 0x270: start of code (after jump from 0x200) */
- char codestart[1];
- } __attribute__ ((packed)) *stage2;
-
- if (data[ndata].size < sizeof(struct grub_stage2_patch_area)) {
- error
- ("The file specified by grub=<loader> is too small to be stage2 of GRUB Legacy.\n");
- goto bail;
- }
-
- stage2 = data[ndata].data;
+ sect_area = (void *)data[ndata].data;
+ data[ndata].base = load_base;
+ data[ndata].size = SECTOR;
+ sidx = ndata;
+ ndata++;
+ }
- /*
- * Check the compatibility version number to see if we loaded a real
- * stage2 file or a stage2 file that we support.
- */
- if (stage2->compat_version_major != 3
- || stage2->compat_version_minor != 2) {
- error
- ("The file specified by grub=<loader> is not a supported stage2 GRUB Legacy binary\n");
- goto bail;
- }
+ /* Mangle file area */
- /* jump 0x200 bytes into the loadfile */
- regs.ip = 0x200;
-
- /*
- * GRUB Legacy wants the partition number in the install_partition
- * variable, located at offset 0x208 of stage2.
- * When GRUB Legacy is loaded, it is located at memory address 0x8208.
- *
- * It looks very similar to the "boot information format" of the
- * Multiboot specification:
- * http://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Boot-information-format
- *
- * 0x208 = part3: sub-partition in sub-partition part2
- * 0x209 = part2: sub-partition in top-level partition
- * 0x20a = part1: top-level partition number
- * 0x20b = drive: BIOS drive number (must be 0)
- *
- * GRUB Legacy doesn't store the BIOS drive number at 0x20b, but at
- * another location.
- *
- * Partition numbers always start from zero.
- * Unused partition bytes must be set to 0xFF.
- *
- * We only care about top-level partition, so we only need to change
- * "part1" to the appropriate value:
- * -1: whole drive (default) (-1 = 0xFF)
- * 0-3: primary partitions
- * 4-*: logical partitions
- */
- stage2->install_partition.part1 = cur_part->index - 1;
-
- /*
- * Grub Legacy reserves 89 bytes (from 0x8217 to 0x826f) for the
- * config filename. The filename passed via grubcfg= will overwrite
- * the default config filename "/boot/grub/menu.lst".
- */
- if (opt.grubcfg) {
- if (strlen(opt.grubcfg) > sizeof(stage2->config_file) - 1) {
- error
- ("The config filename length can't exceed 88 characters.\n");
- goto bail;
- }
-
- strcpy((char *)stage2->config_file, opt.grubcfg);
- }
- }
+ if (opt.isolinux && mangle_isolinux(data + fidx))
+ goto bail;
- /*
- * Dell's DRMK chainloading.
- */
- if (opt.drmk) {
- /* DRMK entry is different than MS-DOS/PC-DOS */
- /*
- * A new size, aligned to 16 bytes to ease use of ds:[bp+28].
- * We only really need 4 new, usable bytes at the end.
- */
- int tsize = (data[ndata].size + 19) & 0xfffffff0;
- regs.ss = regs.fs = regs.gs = 0; /* Used before initialized */
- if (!realloc(data[ndata].data, tsize)) {
- error("Failed to realloc for DRMK\n");
- goto bail;
- }
- data[ndata].size = tsize;
- /* ds:[bp+28] must be 0x0000003f */
- regs.ds = (tsize >> 4) + (opt.seg - 2);
- /* "Patch" into tail of the new space */
- *(int *)(data[ndata].data + tsize - 4) = 0x0000003f;
- }
+ if (opt.grldr && mangle_grldr(cur_part, ®s))
+ goto bail;
- ndata++;
- }
+ if (opt.grub && mangle_grublegacy(cur_part, data + fidx, ®s))
+ goto bail;
- if (!opt.loadfile || data[0].base >= 0x7c00 + SECTOR) {
- /* Actually read the boot sector or mbr */
- if (!(data[ndata].data = disk_read_sectors(&cur_part->di, cur_part->start_lba, 1))) {
- error("Couldn't read boot sector or mbr.\n");
- goto bail;
- } else
- sect_area = (void *)data[ndata].data;
+ if (opt.drmk && mangle_drmk(data + fidx, ®s))
+ goto bail;
- data[ndata].size = SECTOR;
- data[ndata].base = load_base;
- /*
- * To boot the Recovery Console of Windows NT/2K/XP we need to write
- * the string "cmdcons\0" to memory location 0000:7C03.
- * Memory location 0000:7C00 contains the bootsector of the partition.
- */
- if (cur_part->index && opt.cmldr) {
- memcpy((char *)data[ndata].data + 3, cmldr_signature,
- sizeof cmldr_signature);
- }
+ /* Mangle bs/mbr area */
- /*
- * Modify the hidden sectors (partition offset) copy in memory;
- * this modifies the field used by FAT and NTFS filesystems, and
- * possibly other boot loaders which use the same format.
- */
- if (cur_part->index && opt.sethidden) {
- *(uint32_t *) ((char *)data[ndata].data + 28) = cur_part->start_lba;
- }
+ /*
+ * To boot the Recovery Console of Windows NT/2K/XP we need to write
+ * the string "cmdcons\0" to memory location 0000:7C03.
+ * Memory location 0000:7C00 contains the bootsector of the partition.
+ */
+ if (cur_part->index && opt.cmldr) {
+ memcpy((char *)data[sidx].data + 3, cmldr_signature,
+ sizeof cmldr_signature);
+ }
- ndata++;
+ /*
+ * Modify the hidden sectors (partition offset) copy in memory;
+ * this modifies the field used by FAT and NTFS filesystems, and
+ * possibly other boot loaders which use the same format.
+ */
+ if (cur_part->index && opt.sethidden) {
+ *(uint32_t *) ((char *)data[sidx].data + 28) = cur_part->start_lba;
}
+
if (cur_part->index) {
if (cur_part->type == typegpt) {
/* Do GPT hand-over, if applicable (as per syslinux/doc/gpt.txt) */
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