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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <err.h>
struct context {
void *buf;
struct {
size_t offset, len;
bool with_offset_and_len;
struct {
FILE *src;
} write;
enum {
MODE_WRITE,
MODE_READ
} mode;
} op;
struct {
FILE *mem;
pid_t pid;
} proc;
};
static void
usage(const char *argv0)
{
fprintf(stderr, "usage: %s pid write file [offset len] < regions\n"
" %s pid read [offset len] < regions\n\n"
" regions must be in /proc/<pid>/maps format", argv0, argv0);
exit(EXIT_FAILURE);
}
static void
context_init(struct context *ctx, int argc, const char *argv[])
{
if (argc < 3)
usage(argv[0]);
*ctx = (struct context){0};
ctx->proc.pid = strtoull(argv[1], NULL, 10);
{
bool w, r;
const char *mode = argv[2];
if ((w = strcmp(mode, "write")) && (r = strcmp(mode, "read")))
err(EXIT_FAILURE, "mode must be write or read");
ctx->op.mode = (!w ? MODE_WRITE : MODE_READ);
}
if (ctx->op.mode == MODE_WRITE && argc < 4)
usage(argv[0]);
if (argc > (ctx->op.mode == MODE_WRITE) + 3) {
if (argc < (ctx->op.mode == MODE_WRITE) + 5)
usage(argv[0]);
ctx->op.offset = strtoull(argv[(ctx->op.mode == MODE_WRITE) + 3], NULL, 10);
ctx->op.len = strtoull(argv[(ctx->op.mode == MODE_WRITE) + 4], NULL, 10);
ctx->op.with_offset_and_len = true;
}
if (ctx->op.mode == MODE_WRITE && !(ctx->op.write.src = fopen(argv[3], "rb")))
err(EXIT_FAILURE, "fopen(%s)", argv[3]);
char path[128];
snprintf(path, sizeof(path), "/proc/%u/mem", ctx->proc.pid);
if (!(ctx->proc.mem = fopen(path, "w+b")))
err(EXIT_FAILURE, "fopen(%s)", path);
}
static void
context_release(struct context *ctx)
{
if (ctx->op.write.src)
fclose(ctx->op.write.src);
fclose(ctx->proc.mem);
free(ctx->buf);
*ctx = (struct context){0};
}
static void
for_each_line_in_file(FILE *f, void (*cb)(const char *line, void *data), void *data)
{
char *buffer = NULL;
size_t step = 1024, allocated = 0, written = 0, read = 0;
do {
if (written + read >= allocated && !(buffer = realloc(buffer, (allocated += step) + 1)))
err(EXIT_FAILURE, "realloc");
buffer[(written += read)] = 0;
size_t ate = 0;
for (char *line = buffer, *nl; (nl = strchr(line, '\n')); line = nl + 1) {
*nl = 0;
cb(line, data);
ate += nl + 1 - line;
}
memmove(buffer, buffer + ate, (written = written - ate));
} while ((read = fread(buffer + written, 1, allocated - written, f)));
free(buffer);
}
static void
region_cb(const char *line, void *data)
{
struct context *ctx = data;
unsigned long start, end, offset;
if (sscanf(line, "%lx-%lx %*s %lx", &start, &end, &offset) < 3) {
warnx("failed to parse mapping:\n%s", line);
return;
}
warnx("%s", line);
offset = (ctx->op.with_offset_and_len ? 0 : offset);
const size_t len = (ctx->op.with_offset_and_len ? ctx->op.len : end - start);
if (start + ctx->op.offset > end) {
warnx("write offset %lx is out of bounds", start + ctx->op.offset);
return;
}
if (len > (end - start - ctx->op.offset)) {
warnx("%zu bytes doesn't fit in the region", len);
return;
}
if (!len)
return;
if (!(ctx->buf = realloc(ctx->buf, len)))
err(EXIT_FAILURE, "realloc");
clearerr(ctx->proc.mem);
if (ctx->op.mode == MODE_WRITE) {
if (fseek(ctx->op.write.src, offset, SEEK_SET) != 0)
err(EXIT_FAILURE, "fseek");
const size_t rd = fread(ctx->buf, 1, len, ctx->op.write.src);
if (fseek(ctx->proc.mem, start + ctx->op.offset, SEEK_SET) != 0)
err(EXIT_FAILURE, "fseek");
const size_t wd = fwrite(ctx->buf, 1, rd, ctx->proc.mem);
if (ferror(ctx->proc.mem)) {
warn("fread(/proc/%u/mem)", ctx->proc.pid);
} else {
warnx("wrote %lu bytes from offset 0x%lx to offset 0x%lx", wd, offset, start + ctx->op.offset);
}
} else {
if (fseek(ctx->proc.mem, start + ctx->op.offset, SEEK_SET) != 0)
err(EXIT_FAILURE, "fseek");
const size_t rd = fread(ctx->buf, 1, len, ctx->proc.mem);
if (ferror(ctx->proc.mem))
warn("fread(/proc/%u/mem)", ctx->proc.pid);
if (fwrite(ctx->buf, 1, rd, stdout) != rd)
err(EXIT_FAILURE, "fwrite");
}
}
int
main(int argc, const char *argv[])
{
struct context ctx;
context_init(&ctx, argc, argv);
if (ptrace(PTRACE_ATTACH, ctx.proc.pid, NULL, NULL) == -1L)
err(EXIT_FAILURE, "ptrace(PTRACE_ATTACH, %u, NULL, NULL)", ctx.proc.pid);
{
int status;
if (waitpid(ctx.proc.pid, &status, 0) == -1 || !WIFSTOPPED(status))
err(EXIT_FAILURE, "waitpid");
}
for_each_line_in_file(stdin, region_cb, &ctx);
ptrace(PTRACE_DETACH, ctx.proc.pid, 1, 0);
context_release(&ctx);
return EXIT_SUCCESS;
}
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