+static void carefully_write(int fd, const void *buf, size_t sz)
+{
+ const unsigned char *p = buf;
+ ssize_t n;
+
+ if (fd < 0) return;
+ while (sz) {
+ n = write(fd, p, sz);
+ if (n < 0) {
+ if (errno == EINTR) continue;
+ bail_syserr(errno, "failed to write to output file");
+ }
+ if (!n) bail("unexpected short write to output file");
+ p += n; sz -= n;
+ }
+}
+
+static void open_file_on_demand(const char *file, FILE **fp_inout,
+ const char *what)
+{
+ FILE *fp;
+
+ if (!*fp_inout) {
+ fp = fopen(file, "w");
+ if (!fp)
+ bail_syserr(errno, "failed to open %s file `%s'", what, file);
+ fprintf(fp, "## %s\n\n", what);
+ *fp_inout = fp;
+ }
+}
+
+static void check_write(FILE *fp, const char *what)
+{
+ fflush(fp);
+ if (ferror(fp)) bail_syserr(errno, "error writing %s file", what);
+}
+
+static void carefully_fclose(FILE *fp, const char *what)
+{
+ if (fp && (ferror(fp) || fclose(fp)))
+ bail_syserr(errno, "error writing %s file", what);
+}
+
+#define DEFVEC(vtype, etype) \
+ typedef struct { etype *v; size_t n, sz; } vtype
+#define VEC_INIT { 0, 0, 0 }
+#define VEC_FREE(vv) do { \
+ free((vv)->v); (vv)->v 0; (vv)->n = (vv)->sz = 0; \
+} while (0)
+#define VEC_PUSH(p, vv) do { \
+ size_t _want; \
+ if ((vv)->n >= (vv)->sz) { \
+ (vv)->sz = (vv)->sz ? 2*(vv)->sz : 32; \
+ _want = (vv)->sz*sizeof(*(vv)->v); \
+ (vv)->v = realloc((vv)->v, _want); \
+ if (!(vv)->v) bail("out of memory allocating %zu bytes", _want); \
+ } \
+ (p) = &(vv)->v[(vv)->n++]; \
+} while (0)
+
+enum { RAW, IFO, VOB, BUP };
+typedef uint_least32_t ident;
+
+static inline ident mkident(unsigned kind, unsigned title, unsigned part)
+ { return (((ident)kind << 0) | ((ident)title << 8) | ((ident)part << 16)); }
+static inline unsigned id_kind(ident id) { return ((id >> 0)&0x0ff); }
+static inline unsigned id_title(ident id) { return ((id >> 8)&0x0ff); }
+static inline unsigned id_part(ident id) { return ((id >> 16)&0x0ff); }
+