Hi Lothar and Alex,
On Fri, May 25, 2018 at 01:26:20PM +0200, Lothar Waßmann wrote:
Hi,
On Fri, 25 May 2018 11:52:17 +0100 Alex Kiernan wrote:
On Fri, May 25, 2018 at 9:38 AM Quentin Schulz quentin.schulz@bootlin.com wrote:
While the `env export` can take as parameters variables to be exported, `env import` does not have such a mechanism of variable selection.
Let's add the ability to add parameters at the end of the command for variables to be imported.
Every env variable from the env to be imported passed by parameter to this command will override the value of the variable in the current env.
If a variable exists in the current env but not in the imported env, if this variable is passed as a parameter to env import, the variable will be unset.
If a variable exists in the imported env, the variable in the current env will be set to the value of the one from the imported env.
All the remaining variables are left untouched.
As the size parameter of env import is positional but optional, let's add the possibility to use the sentinel '-' for when we don't want to give the size parameter (when the env is '\0' terminated) but we pass a list of variables at the end of the command.
env import addr env import addr - env import addr size env import addr - foo1 foo2 env import addr size foo1 foo2
are all valid.
env import -c addr env import -c addr - env import -c addr - foo1 foo2
are all invalid because they don't pass the size parameter required for checking, while the following are valid.
env import addr size env import addr size foo1 foo2
Nothing's changed for the other parameters or the overall behaviour.
One of its use case could be to load a secure environment from the signed U-Boot binary and load only a handful of variables from an other, unsecure, environment without completely losing control of U-Boot.
Signed-off-by: Quentin Schulz quentin.schulz@bootlin.com
v3:
- migrate to env import addr size var... instead of env import -w addr
size so that the list of variables to load is more explicit and the behaviour of env import is closer to the one of env export,
v2:
- use strdup instead of malloc + strcpy,
- NULL-check the result of strdup,
- add common exit path for freeing memory in one unique place,
- store token pointer from strtok within the char** array instead of
strdup-ing token within elements of array,
cmd/nvedit.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/cmd/nvedit.c b/cmd/nvedit.c index 11489b0..18cc4db 100644 --- a/cmd/nvedit.c +++ b/cmd/nvedit.c @@ -1001,7 +1001,7 @@ sep_err:
#ifdef CONFIG_CMD_IMPORTENV /*
- env import [-d] [-t [-r] | -b | -c] addr [size]
- env import [-d] [-t [-r] | -b | -c] addr [size] [var ...]
-d: delete existing environment before importing;otherwise overwrite / append to existing definitions-t: assume text format; either "size" must be given or the@@ -1015,6 +1015,11 @@ sep_err:
addr: memory address to read fromsize: length of input data; if missing, proper '\0'termination is mandatory
if var is set and size should be missing (i.e. '\0'
termination), set size to '-'
var... List of the names of the only variables that get importedfrom
the environment at address 'addr'. Without arguments, thewhole
*/ static int do_env_import(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
environment gets imported.@@ -1026,6 +1031,7 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, int fmt = 0; int del = 0; int crlf_is_lf = 0;
int wl = 0; size_t size;cmd = *argv;@@ -1074,9 +1080,9 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, addr = simple_strtoul(argv[0], NULL, 16); ptr = map_sysmem(addr, 0);
if (argc == 2) {
if (argc >= 2 && strcmp(argv[1], "-")) { size = simple_strtoul(argv[1], NULL, 16);
} else if (argc == 1 && chk) {
} else if (chk) { puts("## Error: external checksum format must passsize\n");
return CMD_RET_FAILURE; } else {@@ -1098,6 +1104,9 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag, printf("## Info: input data size = %zu = 0x%zX\n", size,
size);
}
if (argc > 2)wl = 1;if (chk) { uint32_t crc; env_t *ep = (env_t *)ptr;@@ -1112,9 +1121,10 @@ static int do_env_import(cmd_tbl_t *cmdtp, int
flag,
ptr = (char *)ep->data; }
if (himport_r(&env_htab, ptr, size, sep, del ? 0 : H_NOCLEAR,crlf_is_lf, 0, NULL) == 0) {
if (!himport_r(&env_htab, ptr, size, sep, del ? 0 : H_NOCLEAR,The addition of a '!' seems like an odd change, but looking at what himport_r() returns, I think you're correct and it's been broken forever.
No. It was if (h_import_r() == 0) before! ^^^^
Exactly, with the added ternary conditions, the line exceeds the 80 characters just for the opening bracket. I just replaced the == 0 with a ! to gain a few precious characters and avoid having to do a:
ret = himport_r(); if (!ret)
But I could do it if wanted.
If I had changed the behaviour of the function, I would have made a separate commit for it so it's not hidden in some unrelated code, so, that's just a cosmetic fix here :)
Quentin