[PATCH v3] Fix const qualifier build errors with recent glibc

["Cédric Le Goater" <clg@redhat.com>]

A recent change in glibc 2.42.9000 [1] changes the return type of
strstr() and other string functions to be 'const char *' when the
input is a 'const char *'.

This breaks the build in various files with errors such as :

  error: initialization discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
    208 |         char *pidstr = strstr(filename, "%");
        |                        ^~~~~~

Fix this by changing the type of the variables that store the result
of these functions to 'const char *'.

[1] https://sourceware.org/git/?p=glibc.git;a=commit;h=cd748a63ab1a7ae846175c532a3daab341c62690

Signed-off-by: Cédric Le Goater <clg@redhat.com>
---

 Most changes are straight forward apart from vubr_parse_host_port.
 Please check.

 Thanks,

 C.

 backends/tpm/tpm_passthrough.c | 2 +-
 block/vmdk.c                   | 2 +-
 block/vvfat.c                  | 2 +-
 gdbstub/gdbstub.c              | 2 +-
 qga/commands-linux.c           | 7 ++++---
 tests/vhost-user-bridge.c      | 2 +-
 ui/ui-hmp-cmds.c               | 2 +-
 util/log.c                     | 2 +-
 8 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/backends/tpm/tpm_passthrough.c b/backends/tpm/tpm_passthrough.c
index b7c7074c2aa3b0d7c1ed70cbcdb83b78fbd7dce8..a9f35ab7d606c79e148620b1a3e6b1d2bde63b7f 100644
--- a/backends/tpm/tpm_passthrough.c
+++ b/backends/tpm/tpm_passthrough.c
@@ -211,7 +211,7 @@ static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
 static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 {
     int fd = -1;
-    char *dev;
+    const char *dev;
     char path[PATH_MAX];
 
     if (tpm_pt->options->cancel_path) {
diff --git a/block/vmdk.c b/block/vmdk.c
index 3b35b63cb5982364f40192eeb2c8585a0265ee40..89e89cd10e3594ad5be044b819ef4b875614e60a 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1089,7 +1089,7 @@ vmdk_open_vmdk4(BlockDriverState *bs, BdrvChild *file, int flags,
 static int vmdk_parse_description(const char *desc, const char *opt_name,
         char *buf, int buf_size)
 {
-    char *opt_pos, *opt_end;
+    const char *opt_pos, *opt_end;
     const char *end = desc + strlen(desc);
 
     opt_pos = strstr(desc, opt_name);
diff --git a/block/vvfat.c b/block/vvfat.c
index 814796d9185f14183194e0421b8c3ef052c81543..e334b9febb16056b3549558666e20bfddc3a22d6 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1826,7 +1826,7 @@ cluster_was_modified(BDRVVVFATState *s, uint32_t cluster_num)
 
 static const char* get_basename(const char* path)
 {
-    char* basename = strrchr(path, '/');
+    const char *basename = strrchr(path, '/');
     if (basename == NULL)
         return path;
     else
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index dd5fb5667ccd3bd4a303fb3f1b442f230cb44ffb..5b2fc06e58dffeabc9ef3b949d95b583c197e5fd 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -362,7 +362,7 @@ static const char *get_feature_xml(const char *p, const char **newp,
      * qXfer:features:read:ANNEX:OFFSET,LENGTH'
      *                     ^p    ^newp
      */
-    char *term = strchr(p, ':');
+    const char *term = strchr(p, ':');
     *newp = term + 1;
     len = term - p;
 
diff --git a/qga/commands-linux.c b/qga/commands-linux.c
index 4a09ddc760cc794be52e0d28fb6e3574d3827442..c639a60a9415c46abe5a2c8ca46dff5669cfdc43 100644
--- a/qga/commands-linux.c
+++ b/qga/commands-linux.c
@@ -403,7 +403,8 @@ static bool build_guest_fsinfo_for_pci_dev(char const *syspath,
     int i, offset, nhosts = 0, pcilen;
     GuestPCIAddress *pciaddr = disk->pci_controller;
     bool has_ata = false, has_host = false, has_tgt = false;
-    char *p, *driver = NULL;
+    const char *p;
+    char *driver = NULL;
     bool ret = false;
 
     p = strstr(syspath, "/devices/pci");
@@ -543,7 +544,7 @@ static bool build_guest_fsinfo_for_nonpci_virtio(char const *syspath,
                                                  Error **errp)
 {
     unsigned int tgt[3];
-    char *p;
+    const char *p;
 
     if (!strstr(syspath, "/virtio") || !strstr(syspath, "/block")) {
         g_debug("Unsupported virtio device '%s'", syspath);
@@ -575,7 +576,7 @@ static bool build_guest_fsinfo_for_ccw_dev(char const *syspath,
                                            Error **errp)
 {
     unsigned int cssid, ssid, subchno, devno;
-    char *p;
+    const char *p;
 
     p = strstr(syspath, "/devices/css");
     if (!p || sscanf(p + 12, "%*x/%x.%x.%x/%*x.%*x.%x/",
diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
index a5c711b1de8e9c164dd1614f4329b8e3c05d0402..019424c2be8df8c8b5c8b6670574bb74cc7ba927 100644
--- a/tests/vhost-user-bridge.c
+++ b/tests/vhost-user-bridge.c
@@ -744,7 +744,7 @@ vubr_run(VubrDev *dev)
 }
 
 static int
-vubr_parse_host_port(const char **host, const char **port, const char *buf)
+vubr_parse_host_port(const char **host, const char **port, char *buf)
 {
     char *p = strchr(buf, ':');
 
diff --git a/ui/ui-hmp-cmds.c b/ui/ui-hmp-cmds.c
index 980a8bbc518c72d000873d63d06dff9ab7b41395..6c93d452c9c43fe72561f036ebc41ab080a83285 100644
--- a/ui/ui-hmp-cmds.c
+++ b/ui/ui-hmp-cmds.c
@@ -418,7 +418,7 @@ err_out:
 void sendkey_completion(ReadLineState *rs, int nb_args, const char *str)
 {
     int i;
-    char *sep;
+    const char *sep;
     size_t len;
 
     if (nb_args != 2) {
diff --git a/util/log.c b/util/log.c
index 41f78ce86b2522b8b7072c8b76d8e18603142db6..c44d66b5ce78338cf1b2cd26b7503cb94d4570cb 100644
--- a/util/log.c
+++ b/util/log.c
@@ -203,7 +203,7 @@ static ValidFilenameTemplateResult
 valid_filename_template(const char *filename, bool per_thread, Error **errp)
 {
     if (filename) {
-        char *pidstr = strstr(filename, "%");
+        const char *pidstr = strstr(filename, "%");
 
         if (pidstr) {
             /* We only accept one %d, no other format strings */
-- 
2.52.0