diff options
| -rw-r--r-- | usr.sbin/ndiscvt/ndiscvt.c | 88 |
1 files changed, 43 insertions, 45 deletions
diff --git a/usr.sbin/ndiscvt/ndiscvt.c b/usr.sbin/ndiscvt/ndiscvt.c index 8c78d54..a24711e 100644 --- a/usr.sbin/ndiscvt/ndiscvt.c +++ b/usr.sbin/ndiscvt/ndiscvt.c @@ -54,27 +54,36 @@ static int insert_padding(void **, int *); extern const char *__progname; /* - * Sections in object code files can be sparse. That is, the - * section may occupy more space in memory that it does when - * stored in a disk file. In Windows PE files, each section header - * has a 'virtual size' and 'raw data size' field. The latter - * specifies the amount of section data actually stored in the - * disk file, and the former describes how much space the section - * should actually occupy in memory. If the vsize is larger than - * the rsize, we need to allocate some extra storage and fill - * it with zeros. (Think BSS.) + * Sections within Windows PE files are defined using virtual + * and physical address offsets and virtual and physical sizes. + * The physical values define how the section data is stored in + * the executable file while the virtual values describe how the + * sections will look once loaded into memory. It happens that + * the linker in the Microsoft(r) DDK will tend to generate + * binaries where the virtual and physical values are identical, + * which means in most cases we can just transfer the file + * directly to memory without any fixups. This is not always + * the case though, so we have to be prepared to handle files + * where the in-memory section layout differs from the disk file + * section layout. * - * The typical method of loading an executable file involves - * reading each segment into memory using the vaddr/vsize from - * each section header. We try to make a small optimization however - * and only pad/move segments when it's absolutely necessary, i.e. - * if the vsize is larger than the rsize. This conserves a little - * bit of memory, at the cost of having to fixup some of the values - * in the section headers. + * There are two kinds of variations that can occur: the relative + * virtual address of the section might be different from the + * physical file offset, and the virtual section size might be + * different from the physical size (for example, the physical + * size of the .data section might be 1024 bytes, but the virtual + * size might be 1384 bytes, indicating that the data section should + * actually use up 1384 bytes in RAM and be padded with zeros). What we + * do is read the original file into memory and then make an in-memory + * copy with all of the sections relocated, re-sized and zero padded + * according to the virtual values specified in the section headers. + * We then emit the fixed up image file for use by the if_ndis driver. + * This way, we don't have to do the fixups inside the kernel. */ -#define ROUND_UP(x, y) \ - (((x) + (y)) - ((x) % (y))) +#define ROUND_DOWN(n, align) (((uintptr_t)n) & ~((align) - 1l)) +#define ROUND_UP(n, align) ROUND_DOWN(((uintptr_t)n) + (align) - 1l, \ + (align)) #define SET_HDRS(x) \ dos_hdr = (image_dos_header *)x; \ @@ -92,7 +101,7 @@ int insert_padding(imgbase, imglen) image_nt_header *nt_hdr; image_optional_header opt_hdr; int i = 0, sections, curlen = 0; - int offaccum = 0, diff, oldraddr, oldrlen; + int offaccum = 0, oldraddr, oldrlen; uint8_t *newimg, *tmp; newimg = malloc(*imglen); @@ -111,35 +120,24 @@ int insert_padding(imgbase, imglen) SET_HDRS(newimg); for (i = 0; i < sections; i++) { - /* - * If we have accumulated any padding offset, - * add it to the raw data address of this segment. - */ oldraddr = sect_hdr->ish_rawdataaddr; oldrlen = sect_hdr->ish_rawdatasize; - if (offaccum) - sect_hdr->ish_rawdataaddr += offaccum; - if (sect_hdr->ish_misc.ish_vsize > - sect_hdr->ish_rawdatasize) { - diff = ROUND_UP(sect_hdr->ish_misc.ish_vsize - - sect_hdr->ish_rawdatasize, - opt_hdr.ioh_filealign); - offaccum += ROUND_UP(diff - - (sect_hdr->ish_misc.ish_vsize - - sect_hdr->ish_rawdatasize), - opt_hdr.ioh_filealign); - sect_hdr->ish_rawdatasize = - ROUND_UP(sect_hdr->ish_rawdatasize, - opt_hdr.ioh_filealign); - tmp = realloc(newimg, *imglen + offaccum); - if (tmp == NULL) { - free(newimg); - return(ENOMEM); - } - newimg = tmp; - SET_HDRS(newimg); - sect_hdr += i; + sect_hdr->ish_rawdataaddr = sect_hdr->ish_vaddr; + offaccum += ROUND_UP(sect_hdr->ish_vaddr - oldraddr, + opt_hdr.ioh_filealign); + offaccum += + ROUND_UP(sect_hdr->ish_misc.ish_vsize, + opt_hdr.ioh_filealign) - + ROUND_UP(sect_hdr->ish_rawdatasize, + opt_hdr.ioh_filealign); + tmp = realloc(newimg, *imglen + offaccum); + if (tmp == NULL) { + free(newimg); + return(ENOMEM); } + newimg = tmp; + SET_HDRS(newimg); + sect_hdr += i; bzero(newimg + sect_hdr->ish_rawdataaddr, ROUND_UP(sect_hdr->ish_misc.ish_vsize, opt_hdr.ioh_filealign)); |
