From b4caa5393f7a8ac5505c2892b85beb061196b78e Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Sun, 15 Mar 2026 00:51:18 +0100
Subject: build system: use custom depgen instead of gcc

---
 tool/depgen.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 tool/depgen.c

(limited to 'tool')

diff --git a/tool/depgen.c b/tool/depgen.c
new file mode 100644
index 0000000..0291859
--- /dev/null
+++ b/tool/depgen.c
@@ -0,0 +1,153 @@
+#define USAGE "depgen [-MP | -MT target | -MF output] <file>"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char *
+alloc1(size_t n)
+{
+   static char mem[64*1<<10], *pmem = mem;
+   assert(mem+sizeof mem - pmem >= n && "oom");
+   pmem += n;
+   return pmem - n;
+}
+
+static char *
+sdup(const char *s, size_t n)
+{
+   return memcpy(alloc1(n+1), s, n);
+}
+
+static char *
+catpath(const char *s1, const char *s2)
+{
+   if (!s1) return strcpy(alloc1(strlen(s2)+1), s2);
+   size_t n1 = strlen(s1), n2 = strlen(s2), n;
+   char *x = alloc1(n = n1+1+n2+1);
+   memcpy(x, s1, n1);
+   x[n1] = '/';
+   memcpy(x+n1+1, s2, n2);
+   x[n1+n2+1] = 0;
+   for (char *p = x+1; *p; ++p) {
+      if (!memcmp(p, "/../", 4)) {
+         char *next = p+4, *q;
+         for (q = p - 1; q > x && *q != '/'; --q);
+         if (q == x) x = p = next;
+         else {
+            memmove(q+1, next, strlen(next)+1);
+            p = q-1;
+         }
+      }
+   }
+   return x;
+}
+
+static const char *
+fileext(const char *path)
+{
+   assert(path && *path && "empty");
+   const char *dot = NULL;
+   for (++path; *path; ++path) {
+      if (*path == '.') dot = path;
+   }
+   return dot ? dot+1 : "";
+}
+
+static const char *
+withext(const char *path, const char *ext)
+{
+   const char *oext, *file = path;
+   assert(*file && "no filename");
+   oext = fileext(file);
+   size_t len;
+   if (!*oext)
+      len = strlen(file);
+   else
+      len = oext - file - 1;
+   char *res = memcpy(alloc1(len + 1 + (ext ? strlen(ext) + 1 : 0)), file, len);
+   if (ext) {
+      res[len] = '.';
+      memcpy(res + len + 1, ext, strlen(ext));
+   }
+   return res;
+}
+
+static char *
+dirname(const char *path)
+{
+   const char *end = path + strlen(path);
+   while (end > path && *end != '/') --end;
+   return end == path ? NULL : sdup(path, end - path);
+}
+
+static FILE *out;
+
+enum { MAXFILES = 200, MAXLINE = 2048 };
+static const char *files[MAXFILES];
+static int nfiles;
+static int
+dofile(const char *f)
+{
+   int ret = 0;
+   assert(nfiles < MAXFILES);
+   files[nfiles++] = f;
+   FILE *fp = fopen(f, "r");
+   if (!fp) {
+      perror(f);
+      return 1;
+   }
+   char line[MAXLINE], hdr[MAXLINE];
+   while (fgets(line, sizeof line, fp)) {
+      if (sscanf(line, " # include \"%[^\"]\"", hdr) == 1) {
+         const char *abspath = catpath(dirname(f), hdr);
+         for (int i = 0; files[i] && i < MAXFILES; ++i) {
+            if (!strcmp(files[i], abspath)) goto Skip;
+         }
+         fprintf(out, " %s", abspath);
+         ret |= dofile(abspath);
+      }
+   Skip:;
+   }
+   if (ferror(fp)) perror(f);
+   fclose(fp);
+   return ret;
+}
+
+int
+main(int argc, char **argv)
+{
+#define DIE(...) return fprintf(stderr, "? "__VA_ARGS__), fputc('\n', stderr), 1
+   const char *src = NULL, *targ = NULL, *mf = NULL;
+   int mp = 0;
+   for (int i = 1; i < argc; ++i) {
+      if (*argv[i] != '-') {
+         if (src) DIE("too many input files");
+         else src = argv[i];
+      } else if (!strcmp(argv[i], "-MT")) {
+         if (!(targ = argv[++i])) DIE("-MT missing arg");
+      } else if (!strcmp(argv[i], "-MF")) {
+         if (mf) DIE("too many output files\n");
+         if (!(mf = argv[++i])) DIE("-MF missing arg");
+      } else if (!strcmp(argv[i], "-MP")) {
+         mp = 1;
+      } else {
+         DIE("invalid arg '%s'", argv[i]);
+      }
+   }
+   if (!src) return fprintf(stderr, "Usage: "USAGE"\n"), 1;
+   if (mf && !(out = fopen(mf, "w"))) return perror(mf), 1;
+   else if (!out) out = stdout;
+   fprintf(out, "%s: %s", targ ? targ : withext(src, "o"), src);
+   int ret = dofile(src);
+   if (mp) for (int i = 1; files[i]; ++i) {
+      fprintf(out, "\n%s:", files[i]);
+   }
+   fputc('\n', out);
+   if (ferror(out)) ret += 4;
+   fclose(out);
+   return ret;
+}
+
+/* vim:set ts=3 sw=3 expandtab: */
-- 
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