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perform in-place replacement via O_RDWR

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Gautham 2024-12-27 22:24:22 -06:00
parent 47eac0cdad
commit 2c098b35a4
1 changed files with 10 additions and 25 deletions
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35
tool/build/renamestr.c
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@ -39,14 +39,14 @@
"https://github.com/jart/cosmopolitan\n" "https://github.com/jart/cosmopolitan\n"
#define MANUAL \ #define MANUAL \
" -f FROM -t TO -o OUTPUT INPUT \n" \ " -f FROM -t TO INPUT \n" \
"\n" \ "\n" \
"DESCRIPTION\n" \ "DESCRIPTION\n" \
"\n" \ "\n" \
" string replacement in ELF binary .rodata\n" \ " in-place string replacement in ELF binary .rodata\n" \
"\n" \ "\n" \
" this program may be used to replace strings in the\n" \ " this program may be used to replace strings in the\n" \
" .rodata sections of ELF binaries.\n" \ " .rodata sections of ELF binaries, in-place.\n" \
"\n" \ "\n" \
"FLAGS\n" \ "FLAGS\n" \
"\n" \ "\n" \
@ -59,8 +59,6 @@
" -t TO target string replacement. must be shorter\n" \ " -t TO target string replacement. must be shorter\n" \
" than FROM string for replacement to work\n" \ " than FROM string for replacement to work\n" \
"\n" \ "\n" \
" -o OUTPUT output file\n" \
"\n" \
" INPUT ELF binary containing strings to replace\n" \ " INPUT ELF binary containing strings to replace\n" \
"\n" "\n"
@ -69,8 +67,7 @@ static const char *exepath;
static Elf64_Shdr *rodata; static Elf64_Shdr *rodata;
static char *rostart; static char *rostart;
static char *roend; static char *roend;
static const char *outpath; static int exefd;
static int outfd;
static wontreturn void Die(const char *thing, const char *reason) { static wontreturn void Die(const char *thing, const char *reason) {
tinyprint(2, thing, ": ", reason, "\n", NULL); tinyprint(2, thing, ": ", reason, "\n", NULL);
@ -108,8 +105,8 @@ static void Pwrite(const void *data, size_t size, uint64_t offset) {
ssize_t rc; ssize_t rc;
const char *p, *e; const char *p, *e;
for (p = data, e = p + size; p < e; p += (size_t)rc, offset += (size_t)rc) { for (p = data, e = p + size; p < e; p += (size_t)rc, offset += (size_t)rc) {
if ((rc = pwrite(outfd, p, e - p, offset)) == -1) { if ((rc = pwrite(exefd, p, e - p, offset)) == -1) {
DieSys(outpath); DieSys(exepath);
} }
} }
} }
@ -135,19 +132,13 @@ static void GetOpts(int argc, char *argv[]) {
bool partial = false; bool partial = false;
params.n = 0; params.n = 0;
struct Param *param; struct Param *param;
while ((opt = getopt(argc, argv, "hvf:t:o:")) != -1) { while ((opt = getopt(argc, argv, "hvf:t:")) != -1) {
if (params.n >= ARRAYLEN(params.p)) { if (params.n >= ARRAYLEN(params.p)) {
param = NULL; param = NULL;
} else { } else {
param = &(params.p[params.n]); param = &(params.p[params.n]);
} }
switch (opt) { switch (opt) {
case 'o':
if (outpath) {
Die(prog, "outpath already provided");
}
outpath = optarg;
break;
case 'f': case 'f':
if (!param) { if (!param) {
Die(prog, "too many replacements provided"); Die(prog, "too many replacements provided");
@ -199,9 +190,6 @@ static void GetOpts(int argc, char *argv[]) {
Die(prog, "need to_string for replacement"); Die(prog, "need to_string for replacement");
} }
} }
if (!outpath) {
Die(prog, "need outpath to write file");
}
if (optind == argc) { if (optind == argc) {
Die(prog, "missing input argument"); Die(prog, "missing input argument");
} }
@ -389,7 +377,7 @@ static struct Input input;
static void OpenInput(const char *path) { static void OpenInput(const char *path) {
int fd; int fd;
if ((fd = open(path, O_RDONLY)) == -1) if ((fd = open(path, O_RDWR)) == -1)
DieSys(path); DieSys(path);
if ((input.size = lseek(fd, 0, SEEK_END)) == -1) if ((input.size = lseek(fd, 0, SEEK_END)) == -1)
DieSys(path); DieSys(path);
@ -399,7 +387,7 @@ static void OpenInput(const char *path) {
DieSys(path); DieSys(path);
if (!IsElf64Binary(input.elf, input.size)) if (!IsElf64Binary(input.elf, input.size))
Die(path, "not an elf64 binary"); Die(path, "not an elf64 binary");
close(fd); exefd = fd;
} }
static void ReplaceString(struct Param *param) { static void ReplaceString(struct Param *param) {
@ -473,11 +461,8 @@ int main(int argc, char *argv[]) {
} }
#undef NEXT_ROLOC #undef NEXT_ROLOC
if ((outfd = creat(outpath, 0755)) == -1) {
Die(prog, "unable to open file for writing");
}
Pwrite(input.map, input.size, 0); Pwrite(input.map, input.size, 0);
if (close(outfd)) { if (close(exefd)) {
Die(prog, "unable to close file after writing"); Die(prog, "unable to close file after writing");
} }