libflux/buffer: Add trimmed peek/read line variants

For convenience, support flux_buffer_peek_trimmed_line() and
flux_buffer_read_trimmed_line() variants, which will read lines
but strip off any trailing newline characters.

Fixes #1624

src/common/libflux/buffer.c

@@ -445,6 +445,25 @@ const void *flux_buffer_peek_line (flux_buffer_t *fb, int *lenp)
     return fb->buf;
 }
 
+const void *flux_buffer_peek_trimmed_line (flux_buffer_t *fb, int *lenp)
+{
+    int tmp_lenp = 0;
+
+    if (!flux_buffer_peek_line (fb, &tmp_lenp))
+        return NULL;
+
+    if (tmp_lenp) {
+        if (fb->buf[tmp_lenp - 1] == '\n') {
+            fb->buf[tmp_lenp - 1] = '\0';
+            tmp_lenp--;
+        }
+    }
+    if (lenp)
+        (*lenp) = tmp_lenp;
+
+    return fb->buf;
+}
+
 const void *flux_buffer_read_line (flux_buffer_t *fb, int *lenp)
 {
     int ret;
@@ -465,6 +484,25 @@ const void *flux_buffer_read_line (flux_buffer_t *fb, int *lenp)
     return fb->buf;
 }
 
+const void *flux_buffer_read_trimmed_line (flux_buffer_t *fb, int *lenp)
+{
+    int tmp_lenp = 0;
+
+    if (!flux_buffer_read_line (fb, &tmp_lenp))
+        return NULL;
+
+    if (tmp_lenp) {
+        if (fb->buf[tmp_lenp - 1] == '\n') {
+            fb->buf[tmp_lenp - 1] = '\0';
+            tmp_lenp--;
+        }
+    }
+    if (lenp)
+        (*lenp) = tmp_lenp;
+
+    return fb->buf;
+}
+
 int flux_buffer_write_line (flux_buffer_t *fb, const char *data)
 {
     int ret;

src/common/libflux/buffer.h

@@ -74,13 +74,21 @@ int flux_buffer_drop_line (flux_buffer_t *fb);
  */
 const void *flux_buffer_peek_line (flux_buffer_t *fb, int *lenp);
 
+/* Identical to flux_buffer_peek_line(), but does not return trailing
+ * newline */
+const void *flux_buffer_peek_trimmed_line (flux_buffer_t *fb, int *lenp);
+
 /* Read a line in the buffer and mark data as consumed.  Return buffer
  * will include newline.  Optionally return length of data returned in
  * [lenp].  If no line is available, returns pointer and length of 0.
  * Return NULL on error.
  */
 const void *flux_buffer_read_line (flux_buffer_t *fb, int *lenp);
 
+/* Identical to flux_buffer_read_line(), but does not return trailing
+ * newline */
+const void *flux_buffer_read_trimmed_line (flux_buffer_t *fb, int *lenp);
+
 /* Write NUL terminated string data into the buffer and appends a
  * newline.  Returns number of bytes written on success.
  */

src/common/libflux/test/buffer.c

@@ -157,6 +157,45 @@ void basic (void)
     ok (flux_buffer_lines (fb) == 0,
         "flux_buffer_lines returns 0 after drop_line");
 
+    /* write_line & peek_trimmed_line tests */
+
+    ok (flux_buffer_lines (fb) == 0,
+        "flux_buffer_lines returns 0 on no line");
+
+    ok (flux_buffer_write_line (fb, "foo") == 4,
+        "flux_buffer_write_line works");
+
+    ok (flux_buffer_bytes (fb) == 4,
+        "flux_buffer_bytes returns length of bytes written");
+
+    ok (flux_buffer_space (fb) == (FLUX_BUFFER_TEST_MAXSIZE - 4),
+        "flux_buffer_space returns length of space left");
+
+    ok (flux_buffer_lines (fb) == 1,
+        "flux_buffer_lines returns 1 on line written");
+
+    ok ((ptr = flux_buffer_peek_trimmed_line (fb, &len)) != NULL
+        && len == 3,
+        "flux_buffer_peek_trimmed_line works");
+
+    ok (!memcmp (ptr, "foo", 3),
+        "flux_buffer_peek_trimmed_line returns expected data");
+
+    ok (flux_buffer_bytes (fb) == 4,
+        "flux_buffer_bytes returns unchanged length after peek_trimmed_line");
+
+    ok (flux_buffer_drop_line (fb) == 4,
+        "flux_buffer_drop_line works");
+
+    ok (flux_buffer_bytes (fb) == 0,
+        "flux_buffer_bytes returns 0 after drop_line");
+
+    ok (flux_buffer_space (fb) == FLUX_BUFFER_TEST_MAXSIZE,
+        "flux_buffer_space initially returns FLUX_BUFFER_TEST_MAXSIZE");
+
+    ok (flux_buffer_lines (fb) == 0,
+        "flux_buffer_lines returns 0 after drop_line");
+
     /* write_line & read_line tests */
 
     ok (flux_buffer_lines (fb) == 0,
@@ -190,6 +229,39 @@ void basic (void)
     ok (flux_buffer_lines (fb) == 0,
         "flux_buffer_lines returns 0 after read_line");
 
+    /* write_line & read_trimmed_line tests */
+
+    ok (flux_buffer_lines (fb) == 0,
+        "flux_buffer_lines returns 0 on no line");
+
+    ok (flux_buffer_write_line (fb, "foo") == 4,
+        "flux_buffer_write_line works");
+
+    ok (flux_buffer_bytes (fb) == 4,
+        "flux_buffer_bytes returns length of bytes written");
+
+    ok (flux_buffer_space (fb) == (FLUX_BUFFER_TEST_MAXSIZE - 4),
+        "flux_buffer_space returns length of space left");
+
+    ok (flux_buffer_lines (fb) == 1,
+        "flux_buffer_lines returns 1 on line written");
+
+    ok ((ptr = flux_buffer_read_trimmed_line (fb, &len)) != NULL
+        && len == 3,
+        "flux_buffer_read_trimmed_line works");
+
+    ok (!memcmp (ptr, "foo", 3),
+        "flux_buffer_read_trimmed_line returns expected data");
+
+    ok (flux_buffer_bytes (fb) == 0,
+        "flux_buffer_bytes returns 0 after read_trimmed_line");
+
+    ok (flux_buffer_space (fb) == FLUX_BUFFER_TEST_MAXSIZE,
+        "flux_buffer_space initially returns FLUX_BUFFER_TEST_MAXSIZE");
+
+    ok (flux_buffer_lines (fb) == 0,
+        "flux_buffer_lines returns 0 after read_trimmed_line");
+
     /* peek_to_fd tests */
 
     ok (flux_buffer_write (fb, "foo", 3) == 3,
@@ -914,9 +986,15 @@ void corner_case (void)
     ok (flux_buffer_peek_line (NULL, NULL) == NULL
         && errno == EINVAL,
         "flux_buffer_peek_line fails on NULL pointer");
+    ok (flux_buffer_peek_trimmed_line (NULL, NULL) == NULL
+        && errno == EINVAL,
+        "flux_buffer_peek_trimmed_line fails on NULL pointer");
     ok (flux_buffer_read_line (NULL, NULL) == NULL
         && errno == EINVAL,
         "flux_buffer_read_line fails on NULL pointer");
+    ok (flux_buffer_read_trimmed_line (NULL, NULL) == NULL
+        && errno == EINVAL,
+        "flux_buffer_read_trimmed_line fails on NULL pointer");
     ok (flux_buffer_write_line (NULL, "foo") < 0
         && errno == EINVAL,
         "flux_buffer_write_line fails on NULL pointer");
@@ -946,10 +1024,18 @@ void corner_case (void)
         "flux_buffer_peek_line works when no data available");
     ok (len == 0,
         "flux_buffer_peek_line returns length 0 when no data available");
+    ok ((ptr = flux_buffer_peek_trimmed_line (fb, &len)) != NULL,
+        "flux_buffer_peek_trimmed_line works when no data available");
+    ok (len == 0,
+        "flux_buffer_peek_trimmed_line returns length 0 when no data available");
     ok ((ptr = flux_buffer_read_line (fb, &len)) != NULL,
         "flux_buffer_read_line works when no data available");
     ok (len == 0,
         "flux_buffer_read_line returns length 0 when no data available");
+    ok ((ptr = flux_buffer_read_trimmed_line (fb, &len)) != NULL,
+        "flux_buffer_read_trimmed_line works when no data available");
+    ok (len == 0,
+        "flux_buffer_read_trimmed_line returns length 0 when no data available");
 
     /* callback corner case tests */
 
@@ -1064,9 +1150,15 @@ void corner_case (void)
     ok (flux_buffer_peek_line (fb, NULL) == NULL
         && errno == EINVAL,
         "flux_buffer_peek_line fails on destroyed fb pointer");
+    ok (flux_buffer_peek_trimmed_line (fb, NULL) == NULL
+        && errno == EINVAL,
+        "flux_buffer_peek_trimmed_line fails on destroyed fb pointer");
     ok (flux_buffer_read_line (fb, NULL) == NULL
         && errno == EINVAL,
         "flux_buffer_read_line fails on destroyed fb pointer");
+    ok (flux_buffer_read_trimmed_line (fb, NULL) == NULL
+        && errno == EINVAL,
+        "flux_buffer_read_trimmed_line fails on destroyed fb pointer");
     ok (flux_buffer_write_line (fb, "foo") < 0
         && errno == EINVAL,
         "flux_buffer_write_line fails on destroyed fb pointer");