Add env_dump()

1 files changed, 51 insertions, 0 deletions

diff --git a/src/libstddjb/env_dump.c b/src/libstddjb/env_dump.c
new file mode 100644
index 0000000..e15c6be
--- /dev/null
+++ b/src/libstddjb/env_dump.c
@@ -0,0 +1,51 @@
+/* ISC license. */
+
+#include <sys/stat.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <skalibs/bytestr.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+
+ /* XXX: breaks layering, but really openat() should be supported everywhere */
+#include <skalibs/unix-transactional.h>
+
+#define SUFFIX ":envdump:XXXXXX"
+
+int env_dump (char const *dir, mode_t mode, char const *const *envp)
+{
+  int fd ;
+  size_t dirlen = strlen(dir) ;
+  char tmpdir[dirlen + sizeof(SUFFIX)] ;
+  memcpy(tmpdir, dir, dirlen) ;
+  memcpy(tmpdir + dirlen, SUFFIX, sizeof(SUFFIX)) ;
+  if (!mkdtemp(tmpdir)) return 0 ;
+  fd = open_read(tmpdir) ;
+  if (fd == -1) goto err ;
+  for (; *envp ; envp++)
+  {
+    size_t len = str_chr(*envp, '=') ;
+    size_t vallen = strlen(*envp + len + 1) ;
+    char fn[len + 1] ;
+    memcpy(fn, *envp, len + 1) ;
+    len = openwritenclose_at(fd, fn, *envp + len + 1, vallen) ;
+    if (len < vallen) goto cerr ;
+  }
+  fd_close(fd) ;
+  if (chmod(tmpdir, mode) == -1) goto err ;
+  if (rename(tmpdir, dir) == -1) goto err ;
+  return 1 ;
+
+ cerr:
+  fd_close(fd) ;
+ err:
+  {
+    int e = errno ;
+    rm_rf(tmpdir) ;
+    errno = e ;
+  }
+  return 0 ;
+}