158 lines
3 KiB
C
158 lines
3 KiB
C
#include <u.h>
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#include <libc.h>
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#include "/sys/src/libmach/elf.h"
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enum {
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Page = 4096,
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};
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#define ROUND(n) ((n+Page-1)&~(Page-1))
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Shdr isect, csect;
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static ushort
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GETS(void *a)
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{
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uchar *p = a;
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return p[0] | p[1]<<8;
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}
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static ulong
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GETL(void *a)
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{
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uchar *p = a;
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return p[0] | p[1]<<8 | p[2]<<16 | p[3]<<24;
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}
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static void
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PUTS(void *a, ushort v)
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{
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uchar *p = a;
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p[0] = v;
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p[1] = v>>8;
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}
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static void
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PUTL(void *a, ulong v)
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{
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uchar *p = a;
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p[0] = v;
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p[1] = v>>8;
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p[2] = v>>16;
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p[3] = v>>24;
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}
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void
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copy(int fin, int fout, ulong src, ulong dst, ulong size)
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{
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char buf[Page];
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int n;
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seek(fin, src, 0);
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seek(fout, dst, 0);
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n = Page;
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while (size > 0) {
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if (n > size)
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n = size;
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read(fin, buf, n);
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write(fout, buf, n);
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size -= n;
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}
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}
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void
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main(int argc, char **argv)
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{
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Ehdr e;
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Shdr s;
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Phdr p;
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int efd, ofd, ns, i, n;
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ulong shoff, off, noff, size, msize;
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char *sname, *sval;
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if (argc != 5)
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sysfatal("Usage: xenelf input-elf-file output-elf-file section-name section-contents");
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efd = open(argv[1], OREAD);
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if (efd < 0)
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sysfatal("%s: %r", argv[1]);
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ofd = create(argv[2], OWRITE, 0666);
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if (ofd < 0)
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sysfatal("%s: %r", argv[2]);
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sname = argv[3];
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sval = argv[4];
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read(efd, &e, sizeof e);
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//if (e.shstrndx)
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// sysfatal("section header string index already present");
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/* page-align loadable segments in file */
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ns = GETS(&e.phnum);
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shoff = GETL(&e.phoff);
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noff = shoff+ns*sizeof(Phdr);
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noff = ROUND(noff);
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for (i = 0; i < ns; i++) {
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seek(efd, shoff+i*sizeof(Phdr), 0);
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read(efd, &p, sizeof p);
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off = GETL(&p.offset);
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PUTL(&p.offset, noff);
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size = GETL(&p.filesz);
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copy(efd, ofd, off, noff, size);
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if (GETL(&p.type) == LOAD) {
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size = ROUND(size);
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PUTL(&p.filesz, size);
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if ((msize = GETL(&p.memsz)) != 0 && size > msize)
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PUTL(&p.memsz, size);
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} else {
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/* memory size for symtab segment is actually line number table size */
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msize = GETL(&p.memsz);
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copy(efd, ofd, off+size, noff+size, msize);
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noff += msize;
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}
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noff += size;
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seek(ofd, shoff+i*sizeof(Phdr), 0);
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write(ofd, &p, sizeof p);
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}
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/* append single-entry shstrndx */
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PUTL(&isect.offset, seek(ofd, noff, 0));
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n = strlen(sname);
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PUTL(&isect.size, n+2);
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write(ofd, sname+n, 1);
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write(ofd, sname, n+1);
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/* append comment section contents */
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PUTL(&csect.name, 1);
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PUTL(&csect.offset, seek(ofd, 0, 2));
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n = strlen(sval);
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PUTL(&csect.size, n+1);
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write(ofd, sval, n+1);
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/* copy existing section headers to end */
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ns = 0; //GETS(&e.shnum);
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shoff = GETL(&e.shoff);
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PUTL(&e.shoff, seek(ofd, 0, 2));
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for (i = 0; i < ns; i++) {
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seek(efd, shoff+i*sizeof(Shdr), 0);
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read(efd, &s, sizeof s);
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seek(ofd, 0, 2);
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write(ofd, &s, sizeof s);
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}
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/* append section header for comment section */
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write(ofd, &csect, sizeof csect);
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++ns;
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/* append section header for shstrndx */
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PUTS(&e.shstrndx, ns);
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++ns;
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write(ofd, &isect, sizeof isect);
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/* rewrite elf header */
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PUTS(&e.shentsize, sizeof(Shdr));
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PUTS(&e.shnum, ns);
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seek(ofd, 0, 0);
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write(ofd, &e, sizeof e);
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exits(0);
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}
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