diff options
Diffstat (limited to 'com32/chain/utility.c')
| -rw-r--r-- | com32/chain/utility.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/com32/chain/utility.c b/com32/chain/utility.c new file mode 100644 index 00000000..fb59551b --- /dev/null +++ b/com32/chain/utility.c @@ -0,0 +1,214 @@ +#include <com32.h> +#include <stdint.h> +#include <stdio.h> +#include <errno.h> +#include <unistd.h> +#include <string.h> +#include <syslinux/disk.h> +#include "utility.h" + +static const char *bpbtypes[] = { + [0] = "unknown", + [1] = "2.0", + [2] = "3.0", + [3] = "3.2", + [4] = "3.4", + [5] = "4.0", + [6] = "8.0 (NT+)", + [7] = "7.0", +}; + +void error(const char *msg) +{ + fputs(msg, stderr); +} + +int guid_is0(const struct guid *guid) +{ + return !*(const uint64_t *)guid && !*((const uint64_t *)guid + 1); +} + +void wait_key(void) +{ + int cnt; + char junk; + + /* drain */ + do { + errno = 0; + cnt = read(0, &junk, 1); + } while (cnt > 0 || (cnt < 0 && errno == EAGAIN)); + + /* wait */ + do { + errno = 0; + cnt = read(0, &junk, 1); + } while (!cnt || (cnt < 0 && errno == EAGAIN)); +} + +void lba2chs(disk_chs *dst, const struct disk_info *di, uint64_t lba, uint32_t mode) +{ + uint32_t c, h, s, t; + uint32_t cs, hs, ss; + + /* + * Not much reason here, but if we have no valid CHS geometry, we assume + * "typical" ones to have something to return. + */ + if (di->cbios) { + cs = di->cyl; + hs = di->head; + ss = di->spt; + if (mode == l2c_cadd && cs < 1024 && di->lbacnt > cs*hs*ss) + cs++; + else if (mode == l2c_cmax) + cs = 1024; + } else { + if (di->disk & 0x80) { + cs = 1024; + hs = 255; + ss = 63; + } else { + cs = 80; + hs = 2; + ss = 18; + } + } + + if (lba >= cs*hs*ss) { + s = ss; + h = hs - 1; + c = cs - 1; + } else { + s = ((uint32_t)lba % ss) + 1; + t = (uint32_t)lba / ss; + h = t % hs; + c = t / hs; + } + + (*dst)[0] = h; + (*dst)[1] = s | ((c & 0x300) >> 2); + (*dst)[2] = c; +} + +uint32_t get_file_lba(const char *filename) +{ + com32sys_t inregs; + uint32_t lba; + + /* Start with clean registers */ + memset(&inregs, 0, sizeof(com32sys_t)); + + /* Put the filename in the bounce buffer */ + strlcpy(__com32.cs_bounce, filename, __com32.cs_bounce_size); + + /* Call comapi_open() which returns a structure pointer in SI + * to a structure whose first member happens to be the LBA. + */ + inregs.eax.w[0] = 0x0006; + inregs.esi.w[0] = OFFS(__com32.cs_bounce); + inregs.es = SEG(__com32.cs_bounce); + __com32.cs_intcall(0x22, &inregs, &inregs); + + if ((inregs.eflags.l & EFLAGS_CF) || inregs.esi.w[0] == 0) { + return 0; /* Filename not found */ + } + + /* Since the first member is the LBA, we simply cast */ + lba = *((uint32_t *) MK_PTR(inregs.ds, inregs.esi.w[0])); + + /* Clean the registers for the next call */ + memset(&inregs, 0, sizeof(com32sys_t)); + + /* Put the filename in the bounce buffer */ + strlcpy(__com32.cs_bounce, filename, __com32.cs_bounce_size); + + /* Call comapi_close() to free the structure */ + inregs.eax.w[0] = 0x0008; + inregs.esi.w[0] = OFFS(__com32.cs_bounce); + inregs.es = SEG(__com32.cs_bounce); + __com32.cs_intcall(0x22, &inregs, &inregs); + + return lba; +} + +/* drive offset detection */ +int drvoff_detect(int type, unsigned int *off) +{ + if (bpbV40 <= type && type <= bpbVNT) { + *off = 0x24; + } else if (type == bpbV70) { + *off = 0x40; + } else + return 0; + + return -1; +} + +/* + * heuristics could certainly be improved + */ +int bpb_detect(const uint8_t *sec, const char *tag) +{ + int a, b, c, jmp = -1, rev = 0; + + /* media descriptor check */ + if ((sec[0x15] & 0xF0) != 0xF0) + goto out; + + if (sec[0] == 0xEB) /* jump short */ + jmp = 2 + *(int8_t *)(sec + 1); + else if (sec[0] == 0xE9) /* jump near */ + jmp = 3 + *(int16_t *)(sec + 1); + + if (jmp < 0) /* no boot code at all ? */ + goto nocode; + + /* sanity */ + if (jmp < 0x18 || jmp > 0x1F0) + goto out; + + /* detect by jump */ + if (jmp >= 0x18 && jmp < 0x1E) + rev = bpbV20; + else if (jmp >= 0x1E && jmp < 0x20) + rev = bpbV30; + else if (jmp >= 0x20 && jmp < 0x24) + rev = bpbV32; + else if (jmp >= 0x24 && jmp < 0x46) + rev = bpbV34; + + /* TODO: some better V2 - V3.4 checks ? */ + + if (rev) + goto out; + /* + * BPB info: + * 2.0 == 0x0B - 0x17 + * 3.0 == 2.0 + 0x18 - 0x1D + * 3.2 == 3.0 + 0x1E - 0x1F + * 3.4 ==!2.0 + 0x18 - 0x23 + * 4.0 == 3.4 + 0x24 - 0x45 + * NT ==~3.4 + 0x24 - 0x53 + * 7.0 == 3.4 + 0x24 - 0x59 + */ + +nocode: + a = memcmp(sec + 0x03, "NTFS", 4); + b = memcmp(sec + 0x36, "FAT", 3); + c = memcmp(sec + 0x52, "FAT", 3); /* ext. DOS 7+ bs */ + + if ((sec[0x26] & 0xFE) == 0x28 && !b) { + rev = bpbV40; + } else if (sec[0x26] == 0x80 && !a) { + rev = bpbVNT; + } else if ((sec[0x42] & 0xFE) == 0x28 && !c) { + rev = bpbV70; + } + +out: + printf("BPB detection (%s): %s\n", tag, bpbtypes[rev]); + return rev; +} + +/* vim: set ts=8 sts=4 sw=4 noet: */ |