fixes: improve login environment handling (#114)

* chore(organization): allow nested header and c files

* feat: add shell login "middleware" & etc:
  * lidm now calls `bash` (or other shells, depends on PACKAGE cfg) in
  login mode as a session wrapper to source most env (can be disabled)
  * this fixes a lot of env problems with all `/etc/profile` and more

Extra:
* implemented a musl compatible version of `execvpe` and now lidm should
  search for PATH everywhere it needs to
* `search_path` now also checks if the found binary is properly
  executable
* lidm now uses `confstr` for a decent PATH default if none is found
* logs are unbuffered for cases where debug logs appear empty (exit
  without handlers moment)

* chore: one-time evaluate certain makefile vars

---------

Co-authored-by: grialion <48643945+grialion@users.noreply.github.com>

src/util/path.c

@@ -0,0 +1,64 @@
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "util/path.h"
+
+// returns NULL on any error
+// otherwise it returns the absolute path of the program that MUST BE FREED
+//
+// Should be almost completely posix compliant, except it won't resolve empty
+// PATH entries relative to the cwd
+char* NULLABLE search_path(const char* NNULLABLE for_binary) {
+  if (strchr(for_binary, '/') != NULL) {
+    // skip absolute paths
+    return strdup(for_binary);
+  }
+  char* path_env = getenv("PATH");
+  if (!path_env) return NULL;
+  char* path = strdup(path_env);
+  if (!path) return NULL;
+
+  char* tok = strtok(path, ":");
+  while (tok) {
+    char* bin_path;
+    asprintf(&bin_path, "%s/%s", tok, for_binary);
+    if (!bin_path) {
+      free(path);
+      return NULL;
+    }
+
+    struct stat stat_buf;
+    if (stat(bin_path, &stat_buf) == 0 && access(bin_path, X_OK) == 0) {
+      free(path);
+      return bin_path;
+    }
+
+    free(bin_path);
+    tok = strtok(NULL, ":");
+  }
+
+  free(path);
+  return NULL;
+}
+
+// This is present in glibc ONLY with GNU extensions, this aims to provide a
+// musl compatible variant.
+//
+// Respects errno of exec functions family.
+int execvpe(const char* NNULLABLE file, char* NULLABLE const argv[NNULLABLE],
+            char* NULLABLE const envp[NNULLABLE]) {
+  char* path = search_path(file);
+  if (!path) {
+    errno = ENOENT;
+    return -1;
+  }
+  int ret = execve(path, argv, envp);
+  free(path);
+  return ret;
+}

src/util/utf8.c

@@ -0,0 +1,62 @@
+#include "util/utf8.h"
+
+#define UTF8_CONT_MSK 0b11000000
+#define UTF8_CONT_VAL 0b10000000
+bool utf8_iscont(char byte) {
+  return (byte & UTF8_CONT_MSK) == UTF8_CONT_VAL;
+}
+
+size_t utf8len(const char* str) {
+  size_t len = 0;
+  while (*str != '\0') {
+    if (!utf8_iscont(*(str++))) len++;
+  }
+
+  return len;
+}
+
+size_t utf8len_until(const char* str, const char* until) {
+  size_t len = 0;
+  while (str < until) {
+    if (!utf8_iscont(*(str++))) len++;
+  }
+
+  return len;
+}
+
+size_t utf8trunc(char* str, size_t n) {
+  size_t bytes = 0;
+  while (true) {
+    if (str[bytes] == '\0') break;
+    if (utf8_iscont(str[bytes])) {
+      bytes++;
+      continue;
+    }
+    if (n == 0) {
+      str[bytes] = '\0';
+      break;
+    }
+    bytes++;
+    n--;
+  }
+  return bytes;
+}
+
+const char* utf8back(const char* str) {
+  while (utf8_iscont(*(--str))) {
+  }
+  return str;
+}
+const char* utf8seek(const char* str) {
+  while (utf8_iscont(*(++str))) {
+  }
+  return str;
+}
+
+const char* utf8seekn(const char* str, size_t n) {
+  while (n > 0 && *str != '\0') {
+    str = utf8seek(str);
+    n--;
+  }
+  return str;
+}

src/util/vec.c

@@ -0,0 +1,96 @@
+#include <stdlib.h>
+
+#include "util/vec.h"
+
+const struct Vector VEC_NEW = {
+    .length = 0,
+    .capacity = 0,
+    .pages = NULL,
+};
+
+struct Vector vec_from_raw(void** raw) {
+  size_t len = 0;
+  while (raw[len])
+    len++;
+
+  return (struct Vector){
+      .length = len,
+      .capacity = len,
+      .pages = raw,
+  };
+}
+
+void** vec_as_raw(struct Vector self) {
+  if (vec_push(&self, NULL) != 0) return NULL;
+  return self.pages;
+}
+
+int vec_resize(struct Vector* self, size_t size) {
+  void** new_location =
+      (void**)realloc((void*)self->pages, size * sizeof(void*));
+  if (new_location != NULL) {
+    if (self->length > size) self->length = size;
+    self->capacity = size;
+    self->pages = new_location;
+  } else {
+    return -1;
+  }
+  return 0;
+}
+
+int vec_reserve(struct Vector* self, size_t size) {
+  uint32_t new_capacity = self->capacity;
+  while (self->length + size > new_capacity) {
+    new_capacity = new_capacity + (new_capacity >> 1) +
+                   1; // cap * 1.5 + 1; 0 1 2 4 7 11...
+  }
+  return vec_resize(self, new_capacity);
+}
+
+int vec_reserve_exact(struct Vector* self, size_t size) {
+  uint32_t needed_capacity = self->length + size;
+  if (self->capacity < needed_capacity) {
+    return vec_resize(self, needed_capacity);
+  }
+  return 0;
+}
+
+int vec_push(struct Vector* self, void* item) {
+  int res_ret = vec_reserve(self, 1);
+  if (res_ret != 0) return res_ret;
+
+  self->pages[self->length++] = item;
+  return 0;
+}
+
+void vec_free(struct Vector* self) {
+  while (self->length > 0)
+    free(self->pages[--self->length]);
+
+  vec_clear(self);
+}
+
+void vec_clear(struct Vector* self) {
+  free((void*)self->pages);
+  vec_reset(self);
+}
+
+void vec_reset(struct Vector* self) {
+  *self = (struct Vector){
+      .length = 0,
+      .capacity = 0,
+      .pages = NULL,
+  };
+}
+
+void* vec_pop(struct Vector* self) {
+  if (self->length == 0) return NULL;
+
+  return self->pages[--self->length];
+}
+
+void* vec_get(struct Vector* self, size_t index) {
+  if (index >= self->length) return NULL;
+
+  return self->pages[index];
+}