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util/nvmutil: make cmd_swap its own function again 

previous audits sizecoded nvmutil.c, reducing the sloccount,
but this resulted in unreadable code.

move the swap logic (swap parts) back to its own function,
for clarity.

Signed-off-by: Leah Rowe <leah@libreboot.org>
master
Leah Rowe 2025-01-26 08:47:01 +00:00
parent 3dc1fedbe8
commit b01995d167
1 changed files with 26 additions and 14 deletions
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40
util/nvmutil/nvmutil.c
View File

@ -17,7 +17,8 @@
void cmd_setchecksum(void), cmd_brick(void), swap(int partnum), writeGbe(void),
cmd_dump(void), cmd_setmac(void), readGbe(void), checkdir(const char *path),
macf(int partnum), hexdump(int partnum), openFiles(const char *path),
cmd_copy(void), parseMacString(const char *strMac, uint16_t *mac);
cmd_copy(void), parseMacString(const char *strMac, uint16_t *mac),
cmd_swap(void);
int goodChecksum(int partnum);
uint8_t hextonum(char chs), rhex(void);
@ -46,7 +47,7 @@ typedef struct op {
op_t op[] = {
{ .str = "dump", .cmd = cmd_dump, .args = 3},
{ .str = "setmac", .cmd = cmd_setmac, .args = 3},
{ .str = "swap", .cmd = writeGbe, .args = 3},
{ .str = "swap", .cmd = cmd_swap, .args = 3},
{ .str = "copy", .cmd = cmd_copy, .args = 4},
{ .str = "brick", .cmd = cmd_brick, .args = 4},
{ .str = "setchecksum", .cmd = cmd_setchecksum, .args = 4},
@ -148,8 +149,8 @@ main(int argc, char *argv[])
readGbe(); /* read gbe file into memory */
(*cmd)(); /* operate on gbe file in memory, as per user command */
if ((gbeFileChanged) && (flags != O_RDONLY) && (cmd != writeGbe))
writeGbe(); /* not called for swap cmd; swap calls writeGbe */
if ((gbeFileChanged) && (flags != O_RDONLY))
writeGbe();
err_if((errno != 0) && (cmd != cmd_dump)); /* don't err on dump */
return errno; /* errno can be set by the dump command */
@ -197,7 +198,7 @@ openFiles(const char *path)
void
readGbe(void)
{
if ((cmd == writeGbe) || (cmd == cmd_copy))
if ((cmd == cmd_swap) || (cmd == cmd_copy))
nf = partsize; /* read/write the entire block */
else
nf = 128; /* only read/write the nvm part of the block */
@ -378,6 +379,20 @@ cmd_copy(void)
/* we simply set the right nvm part as changed, and write the file */
}
/* swap contents between the two parts */
void
cmd_swap(void) {
err_if(!(goodChecksum(0) || goodChecksum(1)));
errno = 0;
/* speedhack: swap pointers, not words. (xor swap) */
gbe[0] ^= gbe[1];
gbe[1] ^= gbe[0];
gbe[0] ^= gbe[1];
gbeFileChanged = nvmPartChanged[0] = nvmPartChanged[1] = 1;
}
/* verify nvm part checksum (return 1 if valid) */
int
goodChecksum(int partnum)
@ -398,16 +413,13 @@ goodChecksum(int partnum)
void
writeGbe(void)
{
if (cmd == writeGbe) /* cmd swap calls writeGbE; need valid checksum */
err_if(!(goodChecksum(0) || goodChecksum(1)));
for (int p = 0, x = (cmd == writeGbe) ? 1 : 0; p < 2; p++) {
if ((!nvmPartChanged[p]) && (cmd != writeGbe))
for (int p = 0; p < 2; p++) {
if ((!nvmPartChanged[p]))
continue;
swap(p ^ x); /* swap bytes on big-endian host CPUs */
swap(p); /* swap bytes on big-endian host CPUs */
err_if(pwrite(fd, (uint8_t *) gbe[p ^ x], nf, p * partsize)
err_if(pwrite(fd, (uint8_t *) gbe[p], nf, p * partsize)
== -1);
}
@ -417,8 +429,8 @@ writeGbe(void)
/* swap byte order on big-endian CPUs. swap skipped on little endian */
void
swap(int partnum)
{
swap(int partnum) /* swaps bytes in words, not pointers. */
{ /* not to be confused with cmd_swap */
size_t w, x;
uint8_t *n = (uint8_t *) gbe[partnum];