fileio: add 'enforce_newline' argument to write_string_stream()

Add a flag to control whether write_string_stream() should always enforce a
trailing newline character in the file.

4 files changed, 19 insertions, 9 deletions

diff --git a/src/basic/fileio.c b/src/basic/fileio.c
index 00fb6f8b5c..82b40aa7da 100644
--- a/src/basic/fileio.c
+++ b/src/basic/fileio.c
@@ -27,14 +27,14 @@
 #include "ctype.h"
 #include "fileio.h"
 
-int write_string_stream(FILE *f, const char *line) {
+int write_string_stream(FILE *f, const char *line, bool enforce_newline) {
         assert(f);
         assert(line);
 
         errno = 0;
 
         fputs(line, f);
-        if (!endswith(line, "\n"))
+        if (enforce_newline && !endswith(line, "\n"))
                 fputc('\n', f);
 
         fflush(f);
@@ -55,7 +55,7 @@ int write_string_file(const char *fn, const char *line) {
         if (!f)
                 return -errno;
 
-        return write_string_stream(f, line);
+        return write_string_stream(f, line, true);
 }
 
 int write_string_file_no_create(const char *fn, const char *line) {
@@ -77,7 +77,7 @@ int write_string_file_no_create(const char *fn, const char *line) {
                 return -errno;
         }
 
-        return write_string_stream(f, line);
+        return write_string_stream(f, line, true);
 }
 
 int write_string_file_atomic(const char *fn, const char *line) {
@@ -94,7 +94,7 @@ int write_string_file_atomic(const char *fn, const char *line) {
 
         fchmod_umask(fileno(f), 0644);
 
-        r = write_string_stream(f, line);
+        r = write_string_stream(f, line, true);
         if (r >= 0) {
                 if (rename(p, fn) < 0)
                         r = -errno;
diff --git a/src/basic/fileio.h b/src/basic/fileio.h
index 91d4a0d2d5..989b904c26 100644
--- a/src/basic/fileio.h
+++ b/src/basic/fileio.h
@@ -25,7 +25,7 @@
 
 #include "macro.h"
 
-int write_string_stream(FILE *f, const char *line);
+int write_string_stream(FILE *f, const char *line, bool enforce_newline);
 int write_string_file(const char *fn, const char *line);
 int write_string_file_no_create(const char *fn, const char *line);
 int write_string_file_atomic(const char *fn, const char *line);
diff --git a/src/sleep/sleep.c b/src/sleep/sleep.c
index eee6bc8982..2be63b40c6 100644
--- a/src/sleep/sleep.c
+++ b/src/sleep/sleep.c
@@ -65,7 +65,7 @@ static int write_state(FILE **f, char **states) {
         STRV_FOREACH(state, states) {
                 int k;
 
-                k = write_string_stream(*f, *state);
+                k = write_string_stream(*f, *state, true);
                 if (k == 0)
                         return 0;
                 log_debug_errno(k, "Failed to write '%s' to /sys/power/state: %m",
diff --git a/src/test/test-fileio.c b/src/test/test-fileio.c
index 4c31b776bd..725c2fab4a 100644
--- a/src/test/test-fileio.c
+++ b/src/test/test-fileio.c
@@ -302,17 +302,27 @@ static void test_write_string_stream(void) {
 
         f = fdopen(fd, "r");
         assert_se(f);
-        assert_se(write_string_stream(f, "boohoo") < 0);
+        assert_se(write_string_stream(f, "boohoo", true) < 0);
 
         f = freopen(fn, "r+", f);
         assert_se(f);
 
-        assert_se(write_string_stream(f, "boohoo") == 0);
+        assert_se(write_string_stream(f, "boohoo", true) == 0);
         rewind(f);
 
         assert_se(fgets(buf, sizeof(buf), f));
         assert_se(streq(buf, "boohoo\n"));
 
+        f = freopen(fn, "w+", f);
+        assert_se(f);
+
+        assert_se(write_string_stream(f, "boohoo", false) == 0);
+        rewind(f);
+
+        assert_se(fgets(buf, sizeof(buf), f));
+        printf(">%s<", buf);
+        assert_se(streq(buf, "boohoo"));
+
         unlink(fn);
 }