chunk: Use dynamically allocated buffer in chunk_from_fd()

When acting on files, we can use fstat() to estimate the buffer size. On
non-file FDs, we dynamically increase an allocated buffer.

Additionally we slightly change the function signature to properly handle
zero-length files and add appropriate unit tests.

src/pki/commands/issue.c

@@ -14,6 +14,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -382,7 +383,12 @@ static int issue()
 		{
 			chunk_t chunk;
 
-			chunk = chunk_from_fd(0);
+			if (!chunk_from_fd(0, &chunk))
+			{
+				fprintf(stderr, "%s: ", strerror(errno));
+				error = "reading certificate request failed";
+				goto end;
+			}
 			cert_req = lib->creds->create(lib->creds, CRED_CERTIFICATE,
 										  CERT_PKCS10_REQUEST,
 										  BUILD_BLOB, chunk, BUILD_END);
@@ -425,7 +431,12 @@ static int issue()
 		{
 			chunk_t chunk;
 
-			chunk = chunk_from_fd(0);
+			if (!chunk_from_fd(0, &chunk))
+			{
+				fprintf(stderr, "%s: ", strerror(errno));
+				error = "reading public key failed";
+				goto end;
+			}
 			public = lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_ANY,
 										 BUILD_BLOB, chunk, BUILD_END);
 			free(chunk.ptr);
@@ -562,4 +573,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/keyid.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -89,7 +91,11 @@ static int keyid()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);
@@ -165,4 +171,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/print.c

@@ -22,6 +22,7 @@
 #include <selectors/traffic_selector.h>
 
 #include <time.h>
+#include <errno.h>
 
 /**
  * Print public key information
@@ -510,7 +511,11 @@ static int print()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/pub.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -108,7 +110,11 @@ static int pub()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);
@@ -186,4 +192,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/req.c

@@ -16,6 +16,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -118,7 +119,11 @@ static int req()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading private key failed: %s\n", strerror(errno));
+			return 1;
+		}
 		private = lib->creds->create(lib->creds, CRED_PRIVATE_KEY, type,
 									 BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/self.c

@@ -14,6 +14,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -273,7 +274,12 @@ static int self()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "%s: ", strerror(errno));
+			error = "reading private key failed";
+			goto end;
+		}
 		private = lib->creds->create(lib->creds, CRED_PRIVATE_KEY, type,
 									 BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/verify.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -57,7 +59,11 @@ static int verify()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading certificate failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);