[PATCH 1/3] shell: Fix "read -d ''" behavior

Christian Eggers ceggers at arri.de
Mon Jun 29 15:57:24 UTC 2020


With bash's read builtin it is possible to read from a file (e.g.
device-tree) until the first '\0' character:

IFS= read -r -d '' VARIABLE < file

In busybox ash the -d extension is also implemented, but checking the
read character for '\0' has to be performed after comparing with the
delimiter.

Signed-off-by: Christian Eggers <ceggers at arri.de>
---
 shell/shell_common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/shell/shell_common.c b/shell/shell_common.c
index 12c4a073c..42c4c9c97 100644
--- a/shell/shell_common.c
+++ b/shell/shell_common.c
@@ -209,8 +209,6 @@ shell_builtin_read(struct builtin_read_params *params)
 		}
 
 		c = buffer[bufpos];
-		if (c == '\0')
-			continue;
 		if (!(read_flags & BUILTIN_READ_RAW)) {
 			if (backslash) {
 				backslash = 0;
@@ -225,6 +223,8 @@ shell_builtin_read(struct builtin_read_params *params)
 		}
 		if (c == delim) /* '\n' or -d CHAR */
 			break;
+		if (c == '\0')
+			continue;
 
 		/* $IFS splitting. NOT done if we run "read"
 		 * without variable names (bash compat).
-- 
Christian Eggers
Embedded software developer

Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918
Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH
Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477
Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler



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