8f4dc3b40
Denys Vlasenko
2026-08-31
Subject
platform.h: UNINITIALIZED_VAR() macro for suppressing gcc warnings
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include/platform.h+15 -0
| @@ -151,6 +151,21 @@ | |
| # endif | |
| #endif | |
| + | /* Somewhere after gcc-9, it stopped recognizing "int var = var;" initializer |
| + | * as the "this variable is intentionally not initialized, don't warn" idiom. |
| + | */ |
| + | #if !__GNUC_PREREQ(10,0) |
| + | # define UNINITIALIZED_VAR(var,zero) var = var |
| + | #else |
| + | # define UNINITIALIZED_VAR(var,zero) var = zero |
| + | /* NB: in case newer gcc is able to see that the variable |
| + | * is never used before initialization on all possible code paths, |
| + | * you can use int UNINITIALIZED_VAR(var,var); |
| + | * instead of int UNINITIALIZED_VAR(var,0); |
| + | * and avoid having extra zeroing instruction. |
| + | */ |
| + | #endif |
| + | |
| /* ---- Endian Detection ------------------------------------ */ | |
miscutils/less.c+6 -5
| @@ -469,7 +469,8 @@ static int at_end(void) | |
| */ | |
| static void read_lines(void) | |
| { | |
| - | int ndelay_set, eagain, fdflags; |
| + | int ndelay_set, eagain; |
| + | int UNINITIALIZED_VAR(fdflags, fdflags); |
| char *current_line, *p; | |
| int w = width; | |
| char last_terminated = terminated; | |
| @@ -501,16 +502,16 @@ static void read_lines(void) | |
| // Consider these cases: | |
| // "less FILE": can set O_NONBLOCK on open. | |
| // "true | less": can't. | |
| - | // " { less; cat; } <FILE": can't. And must not confuse cat. |
| + | // "{ less; cat; } <FILE": can't. And must not confuse cat. |
| ndelay_set = -1; // "don't know whether stdin is nonblocking" | |
| eagain = 0; | |
| - | while (1) { /* read lines until we reach cur_fline or wanted_match */ |
| + | while (1) { // read lines until we reach cur_fline or wanted_match |
| *p = '\0'; | |
| terminated = 0; | |
| - | while (1) { /* read chars until we have a line */ |
| + | while (1) { // read chars until we have a line |
| char c; | |
| - | /* if no unprocessed chars left, eat more */ |
| + | // if no unprocessed chars left, eat more |
| if (readpos >= read_size) { | |
| // Read stdin, temporarily make it nonblocking (if it's not already) | |
| if (ndelay_set < 0) { | |
networking/tftp.c+1 -1
| @@ -883,7 +883,7 @@ int tftpd_main(int argc UNUSED_PARAM, char **argv) | |
| len_and_sockaddr *our_lsa; | |
| len_and_sockaddr *peer_lsa; | |
| char *mode, *user_opt; | |
| - | char *local_file = local_file; |
| + | char *UNINITIALIZED_VAR(local_file, NULL); |
| const char *error_msg; | |
| int opt, result, opcode; | |
| IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;) | |
shell/hush.c+7 -7
| @@ -7183,9 +7183,9 @@ static NOINLINE int expand_one_var(o_string *output, int n, char *arg, char **pp | |
| char *p; | |
| char *var; | |
| char exp_op; | |
| - | char exp_save = exp_save; /* for compiler */ |
| + | char UNINITIALIZED_VAR(exp_savech, exp_savech); /* for compiler */ |
| char *exp_saveptr; /* points to expansion operator */ | |
| - | char *exp_word = exp_word; /* for compiler */ |
| + | char *UNINITIALIZED_VAR(exp_word, NULL); /* for compiler */ |
| char arg0; | |
| val = NULL; | |
| @@ -7217,7 +7217,7 @@ static NOINLINE int expand_one_var(o_string *output, int n, char *arg, char **pp | |
| /* ${?}, ${var}, ${var:0}, ${var[:]%0} etc */ | |
| exp_saveptr = var+1 + strcspn(var+1, VAR_ENCODED_SUBST_OPS); | |
| } | |
| - | exp_op = exp_save = *exp_saveptr; |
| + | exp_op = exp_savech = *exp_saveptr; |
| if (exp_op) { | |
| exp_word = exp_saveptr + 1; | |
| if (exp_op == ':') { | |
| @@ -7514,11 +7514,11 @@ static NOINLINE int expand_one_var(o_string *output, int n, char *arg, char **pp | |
| * $ x=; f "${x:-'x y' z}" | |
| * |'x y' z| | |
| */ | |
| - | int use_word = (!val || ((exp_save == ':') && !val[0])); |
| + | int use_word = (!val || ((exp_savech == ':') && !val[0])); |
| if (exp_op == '+') | |
| use_word = !use_word; | |
| debug_printf_expand("expand: op:%c (null:%s) test:%i\n", exp_op, | |
| - | (exp_save == ':') ? "true" : "false", use_word); |
| + | (exp_savech == ':') ? "true" : "false", use_word); |
| if (use_word) { | |
| if (exp_op == '+' || exp_op == '-') { | |
| /* ${var+word} - use alternative value */ | |
| @@ -7545,7 +7545,7 @@ static NOINLINE int expand_one_var(o_string *output, int n, char *arg, char **pp | |
| ? exp_word | |
| : "parameter null or not set" | |
| /* ash has more specific messages, a-la: */ | |
| - | /*: (exp_save == ':' ? "parameter null or not set" : "parameter not set")*/ |
| + | /*: (exp_savech == ':' ? "parameter null or not set" : "parameter not set")*/ |
| ); | |
| //TODO: how interactive bash aborts expansion mid-command? | |
| //It aborts the entire line, returns to prompt: | |
| @@ -7571,7 +7571,7 @@ static NOINLINE int expand_one_var(o_string *output, int n, char *arg, char **pp | |
| } | |
| } /* one of "-=+?" */ | |
| - | *exp_saveptr = exp_save; |
| + | *exp_saveptr = exp_savech; |
| } /* if (exp_op) */ | |
| arg[0] = arg0; | |