Initial commit.

.gitignore

@@ -0,0 +1 @@
+recover-pdfs

recover-pdfs.c

@@ -0,0 +1,103 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#define CHUNK 4096
+
+int match_at(const unsigned char *buf, size_t len, const char *pat) {
+    size_t p = strlen(pat);
+    if (len < p) return 0;
+    return memcmp(buf, pat, p) == 0;
+}
+
+size_t find_in_buffer(const unsigned char *buf, size_t len, const char *pat) {
+    size_t p = strlen(pat);
+    for (size_t i = 0; i + p <= len; i++) {
+        if (memcmp(buf + i, pat, p) == 0)
+            return i;
+    }
+    return (size_t)-1;
+}
+
+void write_pdf(const unsigned char *data, size_t len, int idx, const char *outdir) {
+    char path[512];
+    snprintf(path, sizeof(path), "%s/pdf_%04d.pdf", outdir, idx);
+
+    FILE *f = fopen(path, "wb");
+    if (!f) return;
+
+    fwrite(data, 1, len, f);
+    fclose(f);
+}
+
+int main(int argc, char **argv) {
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <image_file> <output_dir>\n", argv[0]);
+        return 1;
+    }
+
+    const char *infile = argv[1];
+    const char *outdir = argv[2];
+
+    mkdir(outdir, 0755);
+
+    FILE *f = fopen(infile, "rb");
+    if (!f) {
+        perror("open input");
+        return 1;
+    }
+
+    unsigned char *buf = malloc(CHUNK * 2);
+    size_t buf_len = 0;
+    int pdf_count = 0;
+
+    unsigned char *file_data = NULL;
+    size_t file_size = 0;
+    int collecting = 0;
+
+    while (!feof(f)) {
+        size_t r = fread(buf + buf_len, 1, CHUNK, f);
+        buf_len += r;
+
+        size_t i = 0;
+
+        while (i < buf_len) {
+
+            if (!collecting) {
+                if (i + 5 < buf_len && memcmp(buf + i, "%PDF-", 5) == 0) {
+                    collecting = 1;
+                    file_data = malloc(1024);
+                    file_size = 0;
+                }
+            }
+
+            if (collecting) {
+                if (file_size % 1024 == 0) {
+                    file_data = realloc(file_data, file_size + 1024);
+                }
+
+                file_data[file_size++] = buf[i];
+
+                if (file_size > 6) {
+                    if (memmem(file_data, file_size, "%%EOF", 5)) {
+                        write_pdf(file_data, file_size, pdf_count++, outdir);
+                        free(file_data);
+                        file_data = NULL;
+                        file_size = 0;
+                        collecting = 0;
+                    }
+                }
+            }
+
+            i++;
+        }
+
+        buf_len = 0;
+    }
+
+    free(buf);
+    fclose(f);
+
+    return 0;
+}