coredump,basic: generalize O_TMPFILE handling a bit

This moves the O_TMPFILE handling from the coredumping code into common library
code, and generalizes it as open_tmpfile_linkable() + link_tmpfile(). The
existing open_tmpfile() function (which creates an unlinked temporary file that
cannot be linked into the fs) is renamed to open_tmpfile_unlinkable(), to make
the distinction clear. Thus, code may now choose between:

 a) open_tmpfile_linkable() + link_tmpfile()
 b) open_tmpfile_unlinkable()

Depending on whether they want a file that may be linked back into the fs later
on or not.

In a later commit we should probably convert fopen_temporary() to make use of
open_tmpfile_linkable().

Followup for: #3065

1 files changed, 5 insertions, 1 deletions

diff --git a/src/basic/fileio.h b/src/basic/fileio.h
index 8084895ff3..58dbc80c24 100644
--- a/src/basic/fileio.h
+++ b/src/basic/fileio.h
@@ -72,7 +72,6 @@ int fflush_and_check(FILE *f);
 
 int fopen_temporary(const char *path, FILE **_f, char **_temp_path);
 int mkostemp_safe(char *pattern, int flags);
-int open_tmpfile(const char *path, int flags);
 
 int tempfn_xxxxxx(const char *p, const char *extra, char **ret);
 int tempfn_random(const char *p, const char *extra, char **ret);
@@ -82,3 +81,8 @@ int write_timestamp_file_atomic(const char *fn, usec_t n);
 int read_timestamp_file(const char *fn, usec_t *ret);
 
 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space);
+
+int open_tmpfile_unlinkable(const char *directory, int flags);
+int open_tmpfile_linkable(const char *target, int flags, char **ret_path);
+
+int link_tmpfile(int fd, const char *path, const char *target);