Use fshut() to properly flush the output stream

For small images, it could happen that the output stream would not be
flushed before exit(), resulting in a lack of error-reporting on
a full device. Using fflush(), a function I first introduced in sbase,
we do the flushing before returning manually and report errors if they
occurred.

8 files changed, 35 insertions, 6 deletions

diff --git a/ff2jpg.c b/ff2jpg.c
index 78cb122..213f90d 100644
--- a/ff2jpg.c
+++ b/ff2jpg.c
@@ -118,5 +118,5 @@ main(int argc, char *argv[])
 	jpeg_finish_compress(&jcomp);
 	jpeg_destroy_compress(&jcomp);
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/ff2pam.c b/ff2pam.c
index 2c4922c..9a18e6b 100644
--- a/ff2pam.c
+++ b/ff2pam.c
@@ -62,5 +62,5 @@ main(int argc, char *argv[])
 		}
 	}
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/ff2png.c b/ff2png.c
index a00e257..58b3d37 100644
--- a/ff2png.c
+++ b/ff2png.c
@@ -83,5 +83,5 @@ main(int argc, char *argv[])
 	png_write_end(pngs, NULL);
 	png_destroy_write_struct(&pngs, NULL);
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/ff2ppm.c b/ff2ppm.c
index f490d94..746425b 100644
--- a/ff2ppm.c
+++ b/ff2ppm.c
@@ -77,5 +77,5 @@ main(int argc, char *argv[])
 		}
 	}
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/jpg2ff.c b/jpg2ff.c
index 8d51fb6..af7b03c 100644
--- a/jpg2ff.c
+++ b/jpg2ff.c
@@ -90,5 +90,5 @@ main(int argc, char *argv[])
 	jpeg_finish_decompress(&js);
 	jpeg_destroy_decompress(&js);
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/png2ff.c b/png2ff.c
index dd9073c..d76d707 100644
--- a/png2ff.c
+++ b/png2ff.c
@@ -107,5 +107,5 @@ main(int argc, char *argv[])
 	/* clean up */
 	png_destroy_read_struct(&pngs, &pngi, NULL);
 
-	return 0;
+	return fshut(stdout, "<stdout>");
 }
diff --git a/util.c b/util.c
index 7b59d19..ea933ca 100644
--- a/util.c
+++ b/util.c
@@ -82,6 +82,33 @@ parse_mask(const char *s, uint16_t mask[3])
 	return 0;
 }
 
+int
+fshut(FILE *fp, const char *fname)
+{
+	int ret = 0;
+
+	/* fflush() is undefined for input streams by ISO C,
+	 * but not POSIX 2008 if you ignore ISO C overrides.
+	 * Leave it unchecked and rely on the following
+	 * functions to detect errors.
+	 */
+	fflush(fp);
+
+	if (ferror(fp) && !ret) {
+		fprintf(stderr, "%s: ferror %s: %s\n", argv0, fname,
+		        strerror(errno));
+		ret = 1;
+	}
+
+	if (fclose(fp) && !ret) {
+		fprintf(stderr, "%s: fclose %s: %s\n", argv0, fname,
+		        strerror(errno));
+		ret = 1;
+	}
+
+	return ret;
+}
+
 void *
 ereallocarray(void *optr, size_t nmemb, size_t size)
 {
diff --git a/util.h b/util.h
index 93492a5..fcb5257 100644
--- a/util.h
+++ b/util.h
@@ -11,6 +11,8 @@ void ff_write_header(uint32_t width, uint32_t height);
 
 int parse_mask(const char *, uint16_t mask[3]);
 
+int fshut(FILE *, const char *);
+
 #undef reallocarray
 void *reallocarray(void *, size_t, size_t);
 void *ereallocarray(void *optr, size_t nmemb, size_t size);