Provide fallback strtof() for platforms where it is missing

Signed-off-by: Jim Klimov <[email protected]>

common/str.c

@@ -627,3 +627,30 @@ int str_ends_with(const char *s, const char *suff) {
 
 	return (slen >= sufflen) && (!memcmp(s + slen - sufflen, suff, sufflen));
 }
+
+#ifndef HAVE_STRTOF
+# include <errno.h>
+# include <stdio.h>
+float strtof(const char *nptr, char **endptr)
+{
+	double d;
+	int i;
+
+	if (!nptr || !*nptr) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	i = sscanf(nptr, "%f", &d);
+	if (i < 1) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	if (endptr) {
+		*endptr = (char*)nptr + i;
+	}
+
+	return (float)d;
+}
+#endif

configure.ac

@@ -879,7 +879,7 @@ dnl# 	[], [AC_MSG_WARN([Required C library routine not found; try adding __EXTEN
 dnl These appear with CFLAGS="-std=c99 -D_POSIX_C_SOURCE=200112L":
 dnl# Methods below currently do not cause build errors for C99+ modes so are
 dnl# not tested as thoroughly as those further below:
-AC_CHECK_FUNCS(strtok_r fileno sigemptyset sigaction,
+AC_CHECK_FUNCS(strtof strtok_r fileno sigemptyset sigaction,
 	[], [AC_MSG_WARN([Required C library routine not found; try adding -D_POSIX_C_SOURCE=200112L])])
 
 dnl For these we have a fallback implementation via the other,

include/nut_float.h

@@ -57,4 +57,9 @@
 #define d_equal(x, y) ( fabs((double)(x) - (double)(y)) <= DBL_EPSILON )
 #define ld_equal(x, y) ( fabsl((long double)(x) - (long double)(y)) <= LDBL_EPSILON )
 
+#ifndef HAVE_STRTOF
+/* Use fallback from libcommon */
+float strtof(const char *nptr, char **endptr);
+#endif
+
 #endif	/* NUT_FLOAT_H_SEEN */